Calorimetry User Guide

8/10/2019 Calorimetry User Guide

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Virtual ChemLabCalorimetric and Thermochemical Experiments

Student Guide

Brigham Young University


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Table of Contents

Overview..................................................................................................................1

The Calorimetry Laboratory .................................................................................3Quick Start ..........................................................................................................3The Simulation.....................................................................................................5

Overview........................................................................................................5Simulation Principles and Features ...................................................................7

Laboratory.........................................................................................................10Overview......................................................................................................10Transferring Solutions and Solids ................................................................... 13

Analytical Balance .........................................................................................14Overview.................................................................................................14Weighing Solids or Liquids ........................................................................16

Dewar and Coffee Cup Calorimeters ...............................................................16Calibration Heater ....................................................................................16Thermometer........................................................................................... 17Stirrer and Level Meter .............................................................................17

Bomb Calorimeter .........................................................................................17Graph Window.............................................................................................. 18Pull-Down TV................................................................................................18Saving Data..................................................................................................19

Stockroom.........................................................................................................20Overview......................................................................................................20

Selecting Calorimeters and Reagents.............................................................. 21The Metals Cabinet .......................................................................................21Preset Experiments .......................................................................................22

Assignments .................................................................................................22Creating Practice Unknowns ..........................................................................23

Lab Book ........................................................................................................... 24

The Electronic Lab Book .....................................................................................25Overview........................................................................................................... 25Typing/Editing Notes and Inserting Links.............................................................26Navigation ......................................................................................................... 26Functions........................................................................................................... 27Reporting .......................................................................................................... 28Web Options......................................................................................................30


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Overview

Welcome to Virtual ChemLab: Calorimetry , a realistic and sophisticated simulation ofcalorimetric and thermochemical experiments. In this virtual laboratory, students are free tomake the choices and decisions that they would confront in actual calorimetric experiments and,in turn, experience the resulting consequences. As in all Virtual ChemLab laboratories, the mainfocus of the calorimetry laboratory is to allow students the ability to explore and discover, in asafe and level-appropriate setting, the concepts and ideas that are important in the study ofchemical thermodynamics.

The virtual calorimetry laboratory provides students with three different calorimeters that allowthem to measure various thermodynamic processes including heats of combustion, heats ofsolution, heats of reaction, the heat capacity, and the heat of fusion. The calorimeters provided inthe simulations are a classic coffee cup calorimeter, a dewar flask (a better version of a coffeecup), and a bomb calorimeter. The calorimetric method used in each calorimeter is based onmeasuring the temperature change in the calorimeter caused by the different thermodynamic

processes. Students can choose from a wide selection of organic materials to measure the heatsof combustion; salts to measure the heats of solution; acids and bases for heats of reaction;metals and alloys for heat capacity measurements; and ice for a melting process. Boiling pointelevation and freezing point depressions can also be measured. Temperature versus time data can

be graphed during the measurements and saved to the electronic lab book for latter analysis.Systematic and random errors in the mass and volume measurements have been included in thesimulation by introducing buoyancy errors in the mass weighings, volumetric errors in theglassware, and characteristic systematic and random errors in the thermometer measurements.

The Virtual ChemLab simulations are available in a network version, a single user or studentversion, or a CD-Only version. In the network version (a typical computer lab installation)electronic assignments and notebook submissions are handled directly through the local areanetwork or via the web through the web connectivity option. In the single user or student version,there is assumed to be no internet connection to receive assignments or submit results;consequently, the simulations are limited to using paper assignments contained in the VirtualChemLab workbooks or using assignments written by your instructor. However, a studentversion can be enabled to use the web connectivity option, which enables the exchange ofelectronic assignments and notebook results using a regular internet connection. In the CD-Onlyversion, Virtual ChemLab can be run directly off the CD without having to be installed on a harddrive. The CD-Only version comes packaged only with textbooks and cannot be enabled to useelectronic assignments. The CD-Only version is designed explicitly to use workbooks that areincluded with the text. For increased speed the contents of the Virtual ChemLab CD can becopied to and run from the hard drive.

Please note that this users guide provides information principally for the network or web-enabledversion of Virtual ChemLab . While reading through the users guide, keep in mind that a studentversion and CD-Only version of the software are almost identical to a network version except fortwo main differences. (1) In both student and CD-Only versions, the hallway contains anelectronic workbook from which students select experiments that correspond to assignments intheir accompanying real workbooks. Details on using the electronic workbook are given in theGetting Started section of the real workbook. (2) In the initial installed configuration for a


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student version, no electronic assignments can be given or received, although preset and practiceunknowns will be available. Note, however, that a student version can be converted to a web-enabled version by turning on the web connectivity option and creating a local user account.Details on the web connectivity option can be found in the electronic lab book section of thismanual.


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Figure 1. The hallway leading into the different virtual rooms in Virtual ChemLab . TheOrganic Chemistry door accesses the virtual organic laboratory, the Stockroom dooraccesses the Instructor Utilities, and the General Chemistry door accesses fivedifferent general chemistry laboratories.

The Calorimetry Laboratory

Quick StartFrom the hallway (Figure 1), click on the General Chemistry door and enter your password. Ifyou do not know your password, contact your instructor. If you are receiving assignmentsthrough a regular internet connection either at home or in a computer lab (instead of a directclient/server connection), you will need to first create a local user account for the currentcomputer you are using by clicking on the Add New User button. To add a new user, you willneed to provide your user ID, password, and the URL address for your web connection. Thesewill be provided by your instructor. This only needs to be done once for each computer you use.


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If you do not need to receive electronic assignments, click on the Guest button on the card readerto gain access to the laboratory.

If your version contains an electronic workbook on a table in the hallway, you can enter thegeneral chemistry laboratory by clicking on the General Chemistry door or by clicking on the

electronic workbook and selecting an experiment. If you must activate yourself as a user toreceive electronic assignments from your instructor, click on the General Chemistry door andonce inside the laboratory click on any lab book and select the Web Options button. Details onhow to use the web connectivity feature are found in the Electronic Lab Book section below.

Once in the laboratory (shown in Figure 2), you will find five different laboratory benches thatrepresent five different general chemistry laboratories. Mousing over each of these laboratory

benches pops up the name of the selected laboratory. To access the calorimetry laboratory, clickthe second table from the left. On the far right-hand side of the room there is a chalkboard usedto display messages from the instructor or display a summary of assignments. If one or moremessages are available from the instructor, the text Messages will be displayed repeatedly on

the chalkboard. Clicking on the chalkboard will bring up a larger image of the chalkboard wheremessages and assignments can be viewed. Messages can be deleted by clicking on the eraser.

Once inside the calorimetry laboratory, go to the stockroom counter by clicking on thestockroom window. Located inside the stockroom are reagent bottles containing organic or

Figure 2. The general chemistry laboratory. The general chemistry laboratory contains five

different laboratories, each of which is accessed by clicking on the appropriate lab bench. The chalkboard to the right in the laboratory is used to access messages fromthe instructor and to see a summary of assignments.


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combustible compounds, salts, pure metals and alloys, pairs of reagents for reactions, and aclipboard containing a set of predefined experiments. A calorimetric experiment is started byselecting the bomb calorimeter, the coffee cup, or the dewar flask and dragging it to thestockroom counter followed by an organic compound for the bomb calorimeter or a salt, metal,or reaction pair for the coffee cup or dewar calorimeter. Assigned unknowns are selected by

dragging bottles from the left side of the Unknowns shelf, and practice unknowns can bedefined by clicking on the Unknowns sign. Clicking on the green Return to Lab arrow willreturn you to the laboratory where the selected bottles and calorimeters can be dragged to thelaboratory bench.

In the laboratory, the heats of various chemical processes can be measured by observing thetemperature change inside the different calorimeters. The types of thermochemical processes thatcan be measured include the combustion of organic materials in the bomb calorimeter, thedissolution of salts in water, acid/base reactions, dropping hot metals in water, and adding ice towater. The temperature inside the calorimeters is displayed by clicking on the thermometers, andthe temperature as a function of time can be plotted in a graphing window.

Other important items in the laboratory include the pull-down TV in the upper left-hand cornerwhere Help and assignment instructions are accessed. An acceleration button is provided toaccelerate time by a factor of five while performing experiments. The electronic lab book isaccessed by clicking on the lab book lying on the table. The lab book is used to record

procedures, observations, and conclusions. Time and temperature data from the experiments can be saved to the lab book by clicking on the Save button located in the thermometer window or onthe Control Panel. This data is saved in the form of links that can be opened and then copied and

pasted into a spreadsheet program for further calculations and graphing. The general chemistrylaboratory is accessed by clicking on the exit sign.

The SimulationOverview

The primary purpose of the calorimetry simulation is to provide students a realistic environmentwhere they can explore and better understand the concepts in chemical thermodynamics usingfundamental calorimetric methods. In Virtual ChemLab: Calorimetry , experiments are

performed in a framework consistent with the other Virtual ChemLab simulations; that is,students are put into a virtual environment where they are free to choose their reagents andequipment, build a conceptual experiment of their own design, and then experience the resultingconsequences. The focus in the calorimetry simulation is to allow students to measure the heateffects of various chemical and physical processes using equipment that can be found in most

instructional laboratories and some equipment that would be less readily available. From thesemeasurements, students will be able to measure heats of combustion, heats of solution, heats offusion, heat capacity, boiling point elevation, and freezing point depression. These results canthen be used to validate Hesss law; demonstrate the interplay between enthalpy, entropy, andGibbs free energy; calculate heats of formation from heats of combustion; and study the effectsof dissolved solutes on the boiling point and freezing point.


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Three calorimeters are provided in the simulation.The first is a bomb or combustion calorimeter that isa stainless steel container consisting of the bomb,the bomb head, and a screw cap. A small cup thatholds the sample rests on the bomb head. An ignition

wire, roughly 4 cm long, is placed between the two posts and feeds down near the sample. The bomb isassembled by placing the bomb head in the bomband then sealing the bomb with the screw cap. Theassembled bomb is then placed in a bucket of water with approximately 2 L of water, and the

bomb is pressurized with approximately 30 atm of O 2. The heat of combustion of the sample ismeasured by igniting the sample and then measuring the resulting temperature change. Becauseof the large mass of the bomb and water, it will take at least five minutes before a steady state isachieved.

The other two calorimeters are a dewar and a Styrofoam coffee cup.

Both of these are insulating vessels that operate equivalently byreducing the flow of heat into and out of the calorimeter. The dewaris a double-walled glass vessel with an insulating vacuum in between.The dewar has superior insulating characteristics over the coffee cup

but is relatively expensive. Consequently, most instructionallaboratories use a coffee cup for the calorimetric experiments instead.The calorimetric experiments performed with the dewar and coffeecup operate in a similar manner. The dewar or coffee cup contains water or a solution and thenheat is given off by the system (exothermic) or added to the system (endothermic) by a chemicalor physical process such as a reaction, dissolving a salt, adding ice, or dropping in a hot piece ofmetal. The resulting temperature change, as measured by the thermometer, can be used toquantify the heat produced or consumed in the process.

The calculation of the heat produced or consumed by a process, including a combustion reaction

in the bomb calorimeter, is based on the equation C =Q

T where Q is the heat produced or

consumed, T is the temperature changed measured by the thermometer, and C is the heatcapacity of the entire system. If C is known, then the heat can be calculated by rearranging theequation to Q = C T . Measuring T is rather straightforward, however, the trick is knowing theheat capacity of the system. The heat capacity of the system includes the sample being measured(for example, the reaction solution, the water plus the metal, the water and the salt, the water andthe ice, the organic compound) plus the calorimeter (the dewar; coffee cup; or the bomb, water,

and bucket). To a first order approximation for the dewar and coffee cup, the heat capacity of thesystem can be taken as the heat capacity of the solution neglecting the contribution of the dewaror coffee cup. For the coffee cup, this is not necessarily a poor assumption since the coffee cuphas so little mass, but the dewar makes a non-trivial contribution. A further approximation can bemade that the heat capacity of any solution in the calorimeter can be approximated by the heatcapacity of water. These assumptions cannot be applied to the bomb calorimeter since thecombined mass of the bomb and bucket is several kilograms.


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The heat capacity of the system (sample plus calorimeter) can be determined using an electricalcalibration. For the dewar and coffee cup, an electrical heater has been provided where the heatercan be turned on and off, the current going through the heater and the voltage across the heatercan be measured, and the time the heater is on can be measured with a stopwatch. From this, theheat, Q , dissipated by the heater can be calculated using Q = power time = V i t where V is

the voltage across the heater while the heater is on, i is the current going through the heater (inamps), and t is the length of time the heater was on. With Q and the resulting temperature rise,T , caused by the electrical heating, the heat capacity, C , can be calculated using the equation

C =Q

T .

Unfortunately for the bomb calorimeter, the heat capacity of the entire calorimetric systemcannot be determined with an electrical heater. Instead, the calorimeter is calibrated bymeasuring the heat of combustion of a standard (such as benzoic acid), which produces a knownheat per mole of sample. From this, the heat capacity of the calorimetric system can be calculatedusing the same method has described above. For calibration purposes, use H = 3226.9 kJ/mol

or H = 3228 2 kJ/mole for the heat of combustion for benzoic acid where H is the standardstate value and H is the value under the actual conditions in the calorimeter or, in other words,the value that would be measured in the experiment. The 2 kJ/mole uncertainty in H is caused

by changes in the correction from the standard state for differing amounts of sample and O 2 inthe bomb during the combustion.

The calorimetry simulation allows a range of classroom and laboratory applications dependingon the level of the class and the subject being taught. For example, students can perform simple,qualitative experiments and observe the sign of the heating event and its magnitude relative toother processes. Students can also perform careful quantitative measurements where they canaccurately determine the heats of combustion, solution, reaction, or fusion of a large collection ofmaterials. All of these experiments are performed within the context of gaining a fundamentalunderstanding of chemical thermodynamics.

Simulation Principles and Features

The important principles and features forming the foundation of the calorimetry simulation arelisted below.

(1) The calorimeters used in the simulation are modeled after and have heat flow characteristicsthat are quite close to an actual dewar, coffee cup, and bomb calorimeter. Sophisticated heatflow equations have been used to model these characteristics; however, one limitation to the

heat flow equations used in the simulation prevents multiple heating events from occurringsimultaneously. For example, if a solid reagent is added to the solution, the second reagentfor a reaction cannot be added until the dissolution process (or the heating) has finished. In asimilar manner, while the electrical heater is on, reagents and water cannot be added to thecalorimeter.

(2) The thermometer is assumed to have an infinitely fast response time or, in other words, thethermometer is in perfect equilibrium with the solution in the calorimeter.


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(3) For the dewar and coffee cup, a stirrer has been provided to increase the rate that a processreaches equilibrium. If the stirrer is turned off, equilibrium times will be increasedsubstantially. The user does not have control over the stirrer for the bomb calorimeter.

(4)

The heat capacity of the solutions is calculated using the partial molar heat capacities for thevarious constituents of the solution. The simulation does not assume the solution has theheat capacity of water.

(5) The simulation assumes that the heat capacity of the solution is temperature independent.

(6) Keep in mind that the enthalpy for a particular process recorded in the literature or intextbook tables are for the standard state. In the simulation, the heats that are produced for agiven process are not standard state heats since they do not occur in the standard state. Inorder to get results from the simulation to agree with textbook values, the standard statecorrections must be applied.

(7) The barometric pressure in the laboratory will change from day to day but will remainconstant for a given day. The boiling point of a solution will be affected by the current

barometric pressure as well as the presence of any dissolved solutes. The freezing point willalso be affected by the presence of dissolved solutes.

(8) Many of the calorimetric processes modeled in the simulation do not reach equilibrium forseveral minutes. An Acceleration button has been provided that will accelerate time in thelaboratory by a factor of five in order to minimize any unnecessary waiting.

(9) When solids are dissolved in water and when solutions are mixed, the resulting solutionvolumes are calculated using the first-order, partial molar volumes for each ionic andnonionic species in the solution. Using these first-order, partial molar volumes willgenerally produce total volumes that are accurate to within 0.1% to 0.3% of the actualvolume. Suitable estimates of partial molar volumes were made for species not found in theliterature.

(10) The volume of liquids delivered by the graduated cylinders will not be the exact volumes aslabeled on the graduated cylinder. Instead, the volumes delivered will have inaccuracies andrandomness typical of actual graduated cylinders.

(11) Items that are weighed on a balance in air are buoyed up by the air causing the observedmass, as displayed by the balance, to be different than the true mass. This buoyancycorrection is small but does make a statistically significant contribution when accuraciesapproaching 0.1% are needed. The mass readings displayed on the analytical balance in thesimulation are observed masses and have been reverse corrected from the true mass. Thedetails involved in making buoyancy corrections can be lengthy, but the equation that iscommonly used to make the corrections is as follows:


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mtrue = mobs

1 air

weights

1 air

sample

where mtrue is the true mass, mobs is the observed mass, air is the density of air, weights is thedensity of the weights (typically 8.0 g cm -3) and sample is the density of the sample. Thedensity of air can be calculated using a variety of methods, but each requires knowledge ofthe temperature and barometric pressure. The temperature and current barometric pressurefor the day is given on the LED display located on the wall. Note that the barometric

pressure will change from day to day in the virtual laboratory but will remain constant forthe entire day.

(12) The accuracy and point-to-point noise are two sources of error that are intrinsic to each piece of glassware, the analytical balance, and to the thermometers. Appropriately sizederrors of each kind are applied in the simulation to each piece of equipment in order to

provide an opportunity for realistic error analysis.


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LaboratoryOverview

The essential features of the laboratory (shown in Figure 3) are described as follows startingfrom the upper left hand corner of the lab and proceeding clockwise.

Exit. Clicking the exit sign exits the calorimetry laboratory and returns the user to the generalchemistry laboratory.

LED Display. The LED display is used to display the temperature in the laboratory and thecurrent barometric pressure. The temperature or pressure is selected by clicking on theappropriate label on the LED display. Note that the laboratory temperature is fixed at 25 C

but the barometric pressure will change daily. The temperature and pressure are necessary for buoyancy corrections.

Figure 3. The virtual calorimetry laboratory. Each of the different parts of the main laboratoryare labeled. See below for more details.


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Accelerate. Below the LED display is an acceleration button that is used to acceleratelaboratory time. In real time, the clock hand on the button rotates relatively slowly, and inacceleration mode the clock hand moves quickly. The acceleration button is useful whenwaiting for a process to reach the steady state and for establishing foredrifts and afterdrifts

for temperature extrapolations. Note that the time versus temperature data saved in the lab book while in acceleration mode will be a factor of five less dense.

Pull-Down TV. In the upper right-hand corner of the laboratory is a small handle that, whenclicked, pulls down a TV that can display information in three different modes. In assignmentmode, the TV displays the assignment instructions that may be included with the assignmentthat is out in the laboratory. This is intended to allow easy reference to the assignmentinstructions while performing the work in the virtual laboratory. When an assignment has not

been accepted, the assignment mode is left blank. In tutorial mode, the TV displays thecontents of the beakers, graduated cylinders, weigh paper, bomb cup, dewar and coffee cupwhen the cursor is placed over the object. In the help mode, the TV lists the help menu for

the laboratory. Bell . The bell located on the stockroom counter is used to access Help.

Stockroom. Clicking on the stockroom window brings the user to the stockroom counter.While at the stockroom counter, calorimeters, reagents, and metals can be selected from thestockroom shelves and placed on the counter. Note that for the bomb calorimeter, onlyorganics can be selected and for the dewar/coffee cup only metals, salts, and reactions can beselected. Assigned unknowns can be selected from the unknown shelf, and practiceunknowns can be prepared by clicking on the Unknowns label. The clipboard hanging inthe stockroom can also be clicked to select preset experiments or accept an assignment.

Graduated Cylinders. There are four graduated cylinders (10, 25, 50, and 100 mL), and theyare used to measure volumes of reagents and water with intermediate accuracy andreproducibility.

Distilled Water. Distilled water can be added to beakers, graduated cylinders, and thedewar/coffee cup by dragging the object to the sink underneath the distilled water faucet (thefaucet closest to the wall). Distilled water is added as long as the object is kept in the sink.

Ice Bucket. Ice can be added to the dewar, the coffee cup, or a beaker by first clicking on theice bucket to take off the lid and then clicking and dragging a scoop of ice to the object. Eachscoop of ice weighs approximately 25 g. Accurate weighings are needed for someexperiments. There is an approximate 2-minute grace period for ice put into a beaker beforeit will start melting at a normal rate.

Oven. The oven is used to heat metal samples before being placed in the dewar or coffee cup.The oven is opened and closed by clicking on the door, and turned on and off by clicking onthe red and green lights. The oven is normally on. Metal samples are placed in the oven by


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first opening the door and then dragging and dropping the metal sample in the oven. Thetemperature is set clicking on the up and down arrow keys on the temperature display.

Control Panel. The Control Panel is used to control various aspects of the dewar or coffeecup calorimeter. The items that can be controlled include the stirrer, the electrical heater, the

current for the heater, saving data to the lab book, and graphing. The thermometer is turnedon by clicking on the thermometer and stirring can also be turned on by clicking on the stirreritself.

Dewar/Coffee Cup. The dewar and coffee cup operate equivalently and are interchangeablefor performing calorimetric experiments involving metals, salts, ice, and reactions. Thedewar/coffee cup calorimeters consist of the insulating vessel itself, the Control Panel, stirrer,thermometer, and the lid. The lid can be moved to the ring stand on the left so materials can

be added, or materials can be added directly with the lid on and the lid will movemomentarily. With the lid off, the dewar or coffee cup can be dragged to the sink and filledwith water. Clicking on the thermometer opens the thermometer window, and clicking on the

green and red buttons on the stirrer will turn it on and off. Bomb Calorimeter. For combustion experiments, the bomb calorimeter must be selected and

moved on to the laboratory bench (not shown in Figure 3). The Control Panel is built into the bomb calorimeter and is turned on (opening the Control Panel window) by clicking on the panel. Clicking on the calorimeter lid opens it, which exposes the bucket and the bombassembly. The bomb assembly can be clicked and dragged to the bench top and disassembledto expose the bomb cup, and the bomb cup can then be taken to the balance area to loadsamples.

Reagents/Beakers. Reagent bottles from the stockroom can be dragged from the counter and placed on the laboratory bench next to the lab book, the analytical balance, or the oven.Solutions from these bottles can be poured into beakers or graduated cylinders by draggingthe bottle to the desired location and then holding while the solution pours out. Beakers mayalso be placed in the same locations.

Beaker Drawer. Needed beakers for any experiment are obtained by clicking and draggingfrom the beaker drawer or by double-clicking on a beaker in the drawer. Beakers may be

placed in the balance area or on the lab bench in locations highlighted with the spotlight.Water can be added to a beaker by dragging it to the sink and placing it under the distilledwater faucet. Solutions are added to beakers by dragging the bottle, another beaker, or agraduated cylinder to the beaker and holding while the solution is poured out.

Stopwatch. The stopwatch is primarily used to time the electrical heating period whenelectrically calibrating the heat capacity of the dewar or coffee cup calorimeters (see theOverview section in the simulation description). Clicking on the stopwatch opens theStopwatch Window. The stopwatch will automatically start and stop counting (when thewindow is open) when the heater is turned on and off. The stopwatch can also be used totime other events, but the timer must be started manually.


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Lab Book. The lab book is used to record procedures and observations while performingexperiments in the virtual laboratory. Data from the experiments can also be saved as links inthe lab book where it can then be copied and pasted into an external spreadsheet program forfurther analysis.

Balance Area. Clicking on the analytical balance will zoom into the balance area. Whilezoomed in to the balance area, solids can be scooped out of the reagent bottle and then placedon weighing paper or in a beaker for weighing. Organic liquids can also be weighed bydelivering liquid into the bomb cup using the pipet. Items to be weighed must be placed inthe balance area before zooming in. However, items can be dragged off the balance in thenormal lab view. The operation of the analytical balance is similar to those found in typicalinstructional laboratories. Clicking on the Return to Lab arrow will return the user back to thelaboratory view.

Disposal Bucket. The disposal bucket is used to discard beakers, the contents of graduatedcylinders, and the contents of the calorimeters. Clicking on the disposal bucket will clear the

entire laboratory.

Transferring Solutions and Solids

Solutions and solids are generally transferred from a beaker, bottle, graduated cylinder, or weigh paper to another container, including the dewar or coffee cup, by dragging the item with thesolution or solid and dropping it onto another beaker, graduated cylinder, the bomb cup, or thedewar/coffee cup. Details and exceptions to this general rule are given below. Note thatsolutions, reagents, and solids cannot be mixed except in the dewar or coffee cup.

(1) Solutions from bottles can be poured into beakers and the dewar/coffee cup by clicking anddragging the bottle to the object and holding while the solution pours out. The solution willcontinue to pour as long as the bottle is held in place. For beakers and the dewar/coffee cup,spilling will occur if too much solution is added.

(2) To transfer solutions to the graduated cylinders, drag the bottle or beaker containing thesolution and drop it on the selected graduated cylinder. This will transfer enough solution tothe fill the graduate cylinder to the indicated volume. Bottles contain an infinite source ofsolution, but if a beaker does not contain sufficient solution for the selected graduatedcylinder, then the cylinder will only be partially filled.

(3) Solutions in beakers can be transferred to the graduated cylinders, dewar/coffee cup, oranother beaker. This is done by dragging the beaker and dropping it on the selected item. Inthe case of the graduated cylinders, enough solution will be transferred to fill to the top of thecontainer. In the case of another beaker, the entire volume of solution will be transferredfrom the first beaker to the second beaker.

(4) Water can be added to beakers, graduated cylinders, and the dewar/coffee cup by draggingthe beaker or graduated cylinder to the sink and placing it underneath the distilled waterfaucet. Water will continue to be added as long as the beaker or graduated cylinder is in thesink. For beakers, spilling will occur if too much water is added. For graduated cylinders,


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filling will automatically stop when the graduated cylinder is full. Note that water can beadded to an existing solution to dilute it. The dewar/coffee cup can only be filled at the sinkif the lid has been removed.

Analytical Balance

Overview. Clicking on the balance while in the main laboratory zooms into the balance view(shown in Figure 4) where solid reagents, organic liquids, and solutions can be weighed on theanalytical balance. The primary use of the balance in the virtual laboratory is to weigh out solidreagents, organic liquids, metals, water, and ice for the various calorimetric experiments that can

be performed in the laboratory. The essential features of the balance view are described below.

Balance . The simulated balance is modeled after a typical analytical balance with a massresolution of 0.2 mg. Items (beakers, weighing paper, and solids) can be weighed by

Figure 4. The zoomed in or balance view. Each of the different parts of the balance area arelabeled. See below for more details.


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dragging and dropping the item on the balance. The balance has a maximum capacity of 200g. The Tare button can be used to tare or zero out the balance.

Weigh Paper. A piece of weighing paper can be dragged from the stack of papers to eitherthe balance or to the lab bench. Solid can be transferred from the reagent bottle to the

weighing paper in the balance for weighing or onto the weighing paper on the bench top.Any solid on a weighing paper can be dragged and dropped into the beaker.

Beaker. An empty beaker or one with a solution or water can be placed in the balance areafor weighing. The balance area is the only location in the simulated laboratory where solidcan be taken from a reagent bottle and then transferred either to a weighing paper or to a

beaker. Note that solid can also be transferred directly to the beaker while the beaker is onthe balance.

Bomb Cup. The bomb cup (not shown in Figure 4) can also be placed in the balance area for weighing and for the loading of organic solid and liquid

samples. The bomb cup will be located in the same position as the beakershown in Figure 4.

Metals. Metal samples (not shown in Figure 4) can also be placed in the balance area for weighing. The metal sample will be in a glass dish in thesame location as the beaker or bomb cup. The metal sample can beweighed by dragging the sample to the balance with or without a piece ofweighing paper present on the balance. It is recommended that theweighing of metal samples be done before the sample is heated since the metal sample willcool while the sample is in air.

Scoop. The scoop is used to transfer solid from the reagent bottle to either a weighing paper, beaker, or bomb cup. The scoop is used by clicking on the scoop and dragging it to the mouthof the reagent bottle (with the lid off), and then pulling the scoop down the bottle label to oneof the five scoop sizes shown on the label to select the amount of solid to place on the scoop.After solid is on the scoop, it can then be dropped on a weighing paper, beaker, or the bombcup.

Pipet. The pipet is used to transfer liquid organic reagentsfrom the reagent bottle to the bomb cup. The pipet is locatedin the same location as the scoop and replaces the scoopwhen a liquid organic reagent bottle is placed in the balancearea. The pipet is used by clicking on the pipet and draggingit to the mouth of the liquid reagent bottle (with the lid off),and then pulling the pipet down the bottle label to one of the five volumes shown on thelabel. The maximum volume that can be delivered is 1 mL. After the liquid is in the pipet, itcan then be dropped on the bomb cup to deliver the liquid.

Reagent Bottles. Solid and liquid reagents must be placed in the balance area before thereagent can be transferred to a beaker, weigh paper, or the bomb cup. The balance area is the


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only location where solids and liquids can be transferred from the reagent bottles. When a bottle is placed in the balance area, the bottle lid is still on but can be removed by clicking onthe lid. The lid can be replaced by clicking on the mouth of the jar. The bottle label, while inthe balance area, shows scoops or liquid volumes with five different levels. These are used todetermine the amount of reagent to place on the scoop or pipet.

Disposal Bucket. The disposal bucket is used to dispose of weighing paper, the beaker, or todispose of the contents of the bomb cup. Note that if the beaker is dropped on the disposal

bucket, the beaker and its contents will be discarded.

Zoom Out. Clicking on the Zoom Out arrow will return the user to the regular laboratoryview.

Weighing Solids or Liquids . In the calorimetry simulation, solids and liquids are weighed usingthe following sequence: (1) Place the reagent bottle and a beaker or bomb cup in the balance areaand then click on the balance to zoom in. (2) Place either the beaker, weighing paper, or bomb

cup on the balance and then Tare the balance. (3) Click on the reagent bottle lid to open it. (4)Click and drag on the scoop (or pipet for liquids) and place it in the bottle and then, withoutletting go, drag the scoop or pipet down the bottle label to choose the amount of solid or liquid to

place on the scoop or in the pipet. (5) Now drag the scoop to the beaker, weighing paper, or bomb cup on the balance until it snaps in place and drop the scoop or pipet. (6) Repeat thescooping or pipeting step as necessary to measure out the necessary quantity of solid or liquid.(7) If a weighing paper was used to weigh out the solid, drag the weighing paper with solid to the

beaker and drop it to transfer the solid. (8) Note that a beaker, weighing paper, bomb cup, ormetal sample can be dragged from the balance while in the laboratory view.

Dewar and Coffee Cup Calorimeters

The dewar and coffee cup operate equivalently and are interchangeablefor performing calorimetric experiments involving metals, salts, ice,and reactions. The dewar and coffee cup calorimeters consist of theinsulating vessel itself, the Control Panel, stirrer, thermometer, and thelid. The lid can be moved to the ring stand on the left so materials can

be added, filled with water at the sink, or emptied at the disposal bucket. Materials can also be added with the lid on and the lid willmove upward momentarily while a sample or solution is added.Clicking on the thermometer opens the Thermometer Window, andclicking on the green and red buttons on the stirrer will turn stirring onand off. The Control Panel is used to control various aspects of thedewar or coffee cup calorimeter. The items that can be controlledinclude the stirrer, the electrical or calibration heater, the current forthe heater, saving data to the lab book, and graphing.

Calibration Heater . The powersupply for the calibration heaterinside the dewar and coffee cup is a constant current device, and theslider on the Control Panel is used to set the current between 0 and500 mA. The lower LCD is used to display the current setting, and


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the upper LCD is used to display the voltage across the heater. When the voltage or upper LCDreads zero, then the heater is off. The green and red lights on the left of the Control Panel areused to turn the heater on and off. If the Stopwatch Window is open, then the stopwatch willautomatically measure the length of time the heater is on. If the liquid level gets too low in thedewar or coffee cup while the heater is on, the heater will burn out disabling the calibration

heater until the laboratory is cleared. This will be indicated by a blinking red heater light.Thermometer. Clicking on the thermometer will turn onthe thermometer and open the Thermometer Windowwhere the current temperature inside the calorimeter will

be displayed. The Save button on the ThermometerWindow or on the Control Panel is used to save thetemperature as a function of time to the lab book whereit can then be copied and pasted into an externalspreadsheet program for later analysis. The Graph button on the Temperature Window or on theControl Panel is used to open the Graph Window. Details on the Graph Window are described

below. The Units button on the Thermometer Window is used to change the temperature unitsdisplayed in the window.

Stirrer and Level Meter. The green and red buttons on the right side of the Control Panel can beused to turn the stirrer on and off as well as the buttons that are on the stirrer itself. Since thedewar and coffee cup are not transparent, the relative amount of solution in the dewar or coffeecup is shown with the level meter.

Bomb Calorimeter

For combustion experiments, the bomb calorimetermust be selected and moved on to the laboratory

bench. The Control Panel is built into the bombcalorimeter and is turned on (opening the ControlPanel window) by clicking on the LED panel.Clicking on the calorimeter lid opens it, whichexposes the bucket and the bomb assembly. The

bomb assembly can be clicked and dragged to the bench top and disassembled to expose the bomb cup,and the bomb cup can then be taken to the balancearea to load samples. Samples should generally be 1g in size. The bomb is reassembled for a measurement by placing the bomb cup on the bombhead, placing the bomb head in the bomb, and placing the screw cap on top of the bomb. Theassembled bomb can then be taken to the calorimeter and placed in the water bath and the lidclosed.

The combustion experiment is controlled with the bomb Control Panel. The LED on the bombControl Panel is used to display the temperature, O 2 pressure, combustion wire length, and thevolume of water in the water bath. The temperature, of course, is used to measure the heat givenoff from the combustion reaction. The other variables are necessary for the most accuratecalculations but can most often be ignored. These variables are accessed by clicking on the


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appropriate button on the Control Panel. Lastly, the Ignite button is used to ignite the sample in the bomb. Note that because of the large heat capacity of the calorimeter (the bomb, bucket, and the water), it will take over five minutes before a steady state has been reached. Using the Acceleration

button will useful in this situation.

The Save button on the Control Panel is used to save thetemperature as a function of time to the lab book where it canthen be copied and pasted into an external spreadsheet

program for later analysis. The Graph button on the ControlPanel is used to open the Graph Window. Details on theGraph Window are described below. The Units button is usedto change the units displayed in the window for the differentvariables.

Graph WindowLocated on each of the calorimeter ControlPanels and on the Thermometer Window isthe Graph button. Clicking on the Graph

button will bring up a graphing window thatwill plot the temperature as a function oftime. The x-axis is time starting at zero andthe y-axis is the temperature in Celsius. Thetime axis shows the elapsed time since theGraph Window was opened or since thegraph was last cleared. When the time tracereaches the right edge of the graph, the datawill be shifted to the left in one-minute intervals. The Save button will save the graph to the lab

book, and the Clear button will clear the graph. When allowed by the instructor, the GraphWindow is an effective means to monitor a calorimetric experiment, but it is not intended for anyserious data analysis. Data analysis should be performed on the actual data saved to the lab bookusing the Save button located on the Control Panels or on the Thermometer Window.

Pull-Down TV

In the upper left-hand corner of the laboratory above the unit conversion chart is a small handle,which when clicked, pulls down a TV and can display information in three different modes:

Tutorial. The tutorial mode is the default mode for the TV, and its purpose is to show thecontents of beakers, graduated cylinders, and the calorimeters when these items are pointed towith the mouse.

Assignments. In assignment mode, the TV displays the assignment instruction text for thecurrently accepted assignment. This allows easy reference to the instructions while performing


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the work in the virtual laboratory. When an assignment has not been accepted, the assignmentmode is left blank. Note that not all assignments will have instructions associated with them.

Help. In help mode, the table of contents for the laboratory help is listed on the TV. Clicking asubject listed in the table of contents brings up the help window.

Saving Data

An important element in the calorimetry simulation is the ability to save the time versustemperature data from a calorimetric experiment to the lab book and later copy that data to anexternal spreadsheet program for further analysis. This is done by clicking on any of the Save

buttons on the Control Panels or on the Thermometer Window. This, in turn, will create a link inthe electronic lab book where all the time versus temperature data will be saved as thecalorimetric experiment proceeds. The saving process will continue automatically until the Save

button (now labeled Stop ) is clicked again. If the data set becomes too large, then new links will be automatically created. The electronic lab book must be open for data to be saved. Clicking onthe link in the lab book will bring up a data window displaying all the saved data in columns.This data can be selected, copied, and then pasted into an external spreadsheet program forfurther analysis. Note that the Acceleration button governs the density of points saved to the lab

book. At normal laboratory time, the data rate is approximately one point per second. Whenlaboratory time is accelerated, the data rate will be approximately one point per 5 seconds.During the course of the experiment, time acceleration can be adjusted as necessary to increaseor decrease the density of points saved in the lab book.


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Stockroom

Overview

The stockroom (shown in Figure 5) is used to select a calorimeter and reagents for work in the

laboratory, create practice unknowns, or retrieve assigned unknowns from the instructor. Theessential features of the stockroom are described in the following list.

Reagents. Reagents for calorimetry experiments are selected by clicking on the selected bottles from the reagent shelves and dragging them to the stockroom counter. Bottles canalso be selected by double-clicking on the bottle. Bottles are returned to the reagent shelvesin a similar manner. One organic reagent can be selected for combustion experiments, one

Figure 5. The calorimetry stockroom. Reagents and calorimeters for experiments can beselected by dragging the items down to the stockroom counter. Metals are selected byclicking on the metals cabinet. The clipboard is used to select preset experiments orview assignment instructions.


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salt can be selected for dissolution experiments, and a reaction pair can be selected for heatof reaction experiments.

Metals Cabinet. Clicking on the metals cabinet brings the user to a zoomed in view of thecabinet where a pure elemental metal or an alloy sample can be selected for heat capacity

measurements. The cabinet contains four drawers each of which contains sixteen metalsamples. A drawer is opened by clicking on the drawer, and a sample is selected by draggingthe sample to the glass dish to the right of the cabinet. Samples can also be selected bydouble clicking on the sample.

Calorimeters. The calorimeter shelf contains the bomb calorimeter, a dewar, and a coffeecup. The bomb calorimeter is used for combustion experiments, and the dewar and coffeecup are used for the remaining experiments. The dewar and coffee cups operate identically,

but the dewar has superior insulating qualities compared to the coffee cup. A calorimeter isselected by clicking and dragging the calorimeter to the stockroom counter or by doubleclicking. Only one calorimeter is allowed out in the laboratory at a time.

Unknown Shelf. The unknown shelf is used to retrieve assigned and practice unknowns andto create practice unknowns. Assigned unknowns will occupy the left-most positions on theshelf and practice unknowns will occupy the right-most positions. Clicking on theUnknowns sign will zoom into the unknown shelf and allow practice unknowns to bedefined.

Clipboard . Clicking on the clipboard gives access to 15 preset thermodynamic experimentsthat are already predefined and ready to run. Be aware that access to these preset experimentscan be turned off by the instructor. The clipboard also gives access to instructions forassigned unknowns given by the instructor.

Bell . As in most stockrooms, the bell is used to access Help for the stockroom.

Return to Lab Arrow . Clicking the Return to Lab arrow returns the user to the laboratory.

Selecting Calorimeters and Reagents

Calorimeters and reagents for the different calorimetry experiments are selected by clicking onthe chosen calorimeter from the calorimeter shelf or bottles from the reagent shelves anddragging them to the stockroom counter or by double-clicking. The calorimeter and bottles arereturned to their respective shelves in a similar manner. One organic reagent can be selected forcombustion experiments, one salt can be selected for dissolution experiments, and a reaction paircan be selected for heat of reaction experiments. Only one calorimeter can be out in thelaboratory at a time.

The Metals Cabinet

Clicking on the metals cabinet brings the user to a zoomed in view of the cabinet where a pureelemental metal or an alloy sample can be selected for heat capacity measurements. The cabinetcontains four drawers each of which contains sixteen metal samples. A drawer is opened by


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clicking on the drawer, and a sample is selected by dragging the sample to the glass dish to theright of the cabinet. Samples can also be selected by double clicking on the sample. The ZoomOut arrow is used to return to the stockroom view and the metal sample can then be dragged tothe stockroom counter.

Preset ExperimentsWhen allowed by the instructor, the clipboard gives access to a list of 15 calorimetryexperiments that are predefined and ready to run. To select one of these experiments, click on theclipboard and then click on the desired experiment. The appropriate calorimeter and reagents will

be automatically selected and placed on the stockroom counter. Clicking the Return to Lab arrowwill then automatically place the reagents on the table in the laboratory and setup the experiment.If, after having selected the preset experiment from the clipboard, the calorimeter or reagents onthe stockroom counter are touched or moved before returning to the laboratory, the preset natureof the experiment will be turned off and the experiment will have to be setup manually in thelaboratory.

The following point should be kept in mind: The 15 preset experiments that are included with theinstallation cover many of the fundamental calorimetry experiments that demonstratethermodynamic concepts. These preset experiments are only a small set of the large number ofexperiments that can be designed and implemented in this simulation.

Assignments

Below the preset experiments on the clipboard, the next available calorimetry assignment thathas been released by the instructor will be listed. The information given in this assignment areais the assignment number, the title of the assignment, the due date, and the points possible. Acalorimetry assignment consists of one or two reagents or a metal sample placed on the left side

of the unknown shelf. For heats of combustion, heats of solution, and heat capacity assignments,one or two unknowns can be assigned as part of the assignment.

The general purpose of a calorimetry assignment is to measure and then report the heat ofcombustion for organic reagents, the heat of solution for salts, the heat of reaction for reaction

pairs, or the heat capacity of a metal. An assignment is accepted by dragging the unknowns offthe unknown shelf and placing them on the stockroom counter. As part of the assignment,instructions may also be included which can be found on the clipboard by clicking on the View Assignment Instructions label located below the assignment information. The instructions can also be found on the TV while the unknowns are out in the laboratory.

When an assignment has been accepted, two changes are made to the operation of the laboratory.(1) Clicking on the Assignment button on the pull-down TV will display the assignmentinstructions. The assignment instructions on the TV are a reference while doing the work in thelaboratory and will be available as long as the assignment is out in the laboratory. (2) After anassignment has been accepted, a new section is created in the lab book (named with theassignment number) where only the notes and saved data associated with that assignment can berecorded. Each assignment will have its own section, and these sections can only be modifiedwhile the assignment is out in the laboratory. When the experimental work is finished and the


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observations, results, and conclusions have been recorded in the lab book, the assignment issubmitted for grading by clicking on the Report button in the lab book. As part of the reporting

process, the heats of the assigned process (combustion, solution, etc.) will be recorded. Aftersubmitting an assignment, further editing in the assignment section is locked out. See the Reportsection below for more detail.

The laboratory can be put back into a normal exploratory mode by either reporting theassignment, clearing the laboratory by returning the calorimeter or reagents to the stockroom, or

by clicking on the disposal bucket.

Creating Practice Unknowns

Practice unknowns can be generated that will allow students to practice experimental proceduresand calculations for determining the heats of reaction, solution, or combustion or the heatcapacity of a metal without a score being assigned to the result. The practice unknown view

Figure 6. The practice unknown view in the stockroom as accessed by clicking on theUnknowns sign on the unknown shelf. Practice unknowns are created byselecting the type of unknown. Unknowns consist of reagents or metals withrandomly assigned heats of reaction, solution, combustion, or heat capacity.


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(shown in Figure 6 with an organic unknown selected) is accessed by clicking on theUnknowns label on the unknown shelf. The key elements of the unknown view include (a) theselector switch for the unknown type and (b) the Return to Stockroom arrow.

A practice unknown is defined by selecting the type of unknown needed. This is done by either

clicking on the selector switch or by clicking on the label of the desired type of unknown. Thiswill then place an appropriate unknown reagent, metal, or pair of reagents in the case of areaction unknown on the unknown shelf. A heat of reaction, solution, or combustion or a heatcapacity for the metal will be randomly assigned to the unknown. Clicking on the Return toStockroom arrow will zoom out to the normal stockroom view, and the selected unknown will beon the right side of the unknown shelf. Placing the unknown selector switch on None willremove any practice unknowns from the unknown shelf.

After performing the appropriate experiment for the selected unknown, the result of theexperiment is reported in a manner identical to an assigned unknown except the results must bereported in J/g (or kJ/g) for the heat of solution and heat of combustion, J/mol of reagent 1 for

reactions, and J/K g for the heat capacity of the metal.

Lab Book

The laboratory notebook is used to write and save experimental procedures and observations foreach student and to submit the results of assignments. Data from the calorimetry laboratory canalso be saved to the lab book for later reference and more detailed analysis. The notebook isorganized by sections and pages. New pages can be created as needed for each section. The firstsection is labeled Practice and is always the section that is available to the student anytime aninstructor assignment is not out in the laboratory. When an assignment is accepted for the firsttime, a new section is created in the lab book (named with the assignment number) where onlythe notes associated with that assignment can be recorded. Each assignment will have its ownsection, and these sections can only be modified while the assignment is out in the laboratory.Once an assignment has been submitted for grading, no other modifications are allowed. After anassignment has been submitted, an extra page is added to the end of the section where gradinginformation will be posted.

The lab book is launched by clicking once on the lab book located on the bench top. Detailedinformation on how to use the lab book is located in the lab book sections below.


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Electronic Lab Book

Overview

The laboratory notebook is used to write and save experimental procedures and observations foreach student and to submit the results of assignments to the instructor for grading. In addition,TLC plates and NMR and IR spectra from the organic laboratory; detector output from thequantum laboratory; P , V , T , and n data from the gases laboratory; volume, pH/voltage, andconductivity data from titration experiments; and time versus temperature data from thecalorimetry laboratory can be saved in the notebook as well.

The notebook is organized by sections and pages. The section name and current page number forthe section are listed at the top of the page. New pages can be created as needed for each section.The default section is labeled Practice and is always the section that is available to the studentwhen an assignment is not out in the laboratory. When an assignment is accepted for the firsttime, a new section is created in the lab book (named with the assignment number) where onlythe notes associated with that assignment can be recorded. Each assignment will have its ownsection, and these sections can only be modified while the assignment is out in the laboratory.Once an assignment has been submitted for grading, no other modifications are allowed. After an

Figure 7. The electronic lab book used by the student to record notes.


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assignment has been submitted, an extra page is added to the end of the section where gradinginformation will be posted. Note that electronic assignments can only be accepted and submittedfor a client/server installation or when web connectivity has been enabled.

Typing/Editing Notes and Inserting LinksTo start recording notes on the current page, click the page until a cursor appears.

Notes can be typed as normal until the bottom of the page. New pages are not automaticallycreated. Text can be inserted past the end of the page (and accessed using the arrow keys), buttext that extends beyond the end of the page is not accessible to the instructor during grading.Text is always inserted when typed, and text can be deleted with both the forward and backwarddelete keys. Blocks of text can be marked using conventional methods, which in turn, can be cut,copied, and pasted using Ctrl-x, Ctrl-c, and Ctrl-v, respectively, for PC computers or Cmd-x,Cmd-c, and Cmd-v for Macintosh. Mouse clicks or arrow keys are used to move around on the

page. No other keys are defined for the lab book.

When you generate TLC plates, NMR spectra, and IR spectra in the organic laboratory; detectoroutput from the quantum laboratory; P , V , T , and n data from the gases laboratory; volume,

pH/voltage, and conductivity data from the titration laboratory; or time versus temperature datafrom the calorimetry laboratory, you can save these results to the lab book by pressing the Save or Record button on the appropriate window. Each TLC, NMR, IR, detector output, gas data,titration data, or calorimetry data saved in the lab book is saved as a link (in blue or red) with aunique label and is placed on the last line of the current page. Clicking a link displays the saveditem as it was originally shown in the laboratory. NMR spectra and IR spectra saved from thespectra library are labeled as such. Gas, titration, or calorimetry data that were saved during anexperiment are displayed as a table in a display window and can be copied and pasted into aspreadsheet program for further analysis. Links can be deleted from the lab book by deleting theentire link label, and links can be moved by adding or deleting text around a link. Links cannot

be moved using cut (or copy) and paste commands.

NavigationMoving around inside the lab book from page to page and section to section is accomplishedusing the four buttons grouped at the top of the left page of the lab book. The functionality foreach of these buttons is described in the sections that follow.

Prev/Next

The Previous and Next buttons are used to go to the previous or next page in the current section.

If a page in either the downward or the upward direction is not available in the section, the button is grayed out and not active.

Search Notes

The Search Notes button is used to specify a word or an exact phrase that can be searched for inthe current section or in the entire lab book. Shown on the right is the Search dialog area that is

placed on the left page of the lab book when the Search Notes button has been pressed. The text


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box is used to enter the word or words that will be searched for. TheSearch button initiates the search for the word or words typed in thetext box. If a match is found, the page with the match will be shownon the right page of the lab book with the match highlighted. Pressingthe Search button again will search for the next occurrence. After a

match has been found, pressing the OK button will close the Searchdialog and switch the lab book to the new page. Pressing the Cancel button closes the Search dialog and keeps the lab book on the old page. The Current Section and All Sections radio buttons specifywhether the search is to be made on the current section or over allsections in the lab book, respectively.

Go To Page

The Go To Page button is used to jump to any page in any of thesections in the lab book. Shown in theaccompanying figure is the dialog

box that is displayed when the Go ToPage button is pressed. The first boxlists the available sections in the lab

book by name. Clicking one of thesewill then list the available pages forthe highlighted section in the second

box. Clicking one of the pages will switch the lab book to the indicated page and section.Pressing the Cancel button keeps the lab book on the old page.

FunctionsGrouped below the navigation buttons are a set of buttons which perform various functions in thelab book. These functions are described in the sections that follow.

New Page

This button creates a new page at the end of the current section. The button is only active whenyou are on the last page of the section. Pages cannot be inserted elsewhere in the section.

Delete Page

This button deletes the current page in the currently selected section. A warning is given beforethe deletion occurs.

Rename Section

This buttons brings up a dialog box that allows the name ofthe current section to be changed. By default, the first sectionin the lab book is given the name Practice , and other sectionsthat are added to the lab book for each assignment are given


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the name Assignment n where n represents the assignment number. The practice section is forkeeping notes when exploring and learning in the laboratory, and the assignment sections areused for keeping notes during assignments and are eventually graded by the instructor. The

Rename Section function allows these default names to be changed.

PrintThis button brings up a dialog box that allows either the current page or the current section to be

printed to a user-selected printer. Links cannot be printed.

Report

This button allows the current assignment to be submitted to the instructor for grading and isonly active when an assignment is out in the laboratory. Upon submitting an assignment forgrading, further modifications to the assignment section are locked out and an extra page isadded to the end of the section containing grading information specific to the assignment. Theexception to this is when an Inorganic or Titration practice unknown is submitted which only

reveals the actual contents or concentration of the unknown and no grading is performed. If webconnectivity has been enabled (see the Web Options button below) then, after submitting theassignment, the student will be prompted to update these results to the server immediately. IfAutomatic Updates has been selected, this update is performed automatically after submitting theassignment.

Inorganic Assignments Pressing the Report button for an inorganic assignment brings up areport window where the possible cations in the unknown are listed. To report the contents ofthe unknown, click the appropriate tiles corresponding to the cations present in the unknown.For assigned unknowns, these selections can be saved by pressing the Save button allowingthe user to return to the lab for further work on the unknown. The Save button is disabled for

practice unknowns. When the assigned or practice unknown is ready for grading, click theSubmit button, which in turn, brings up a warning box stating that no further modificationscan be made to the assignment. Clicking OK submits the unknown and then marks eachcation in the unknown as correct (green) or incorrect (red). For assigned unknowns, the scoreis also posted, and the entire grading report is written on the last page of the assignmentsection.

Quantum Assignments Pressing the Report button for a quantum assignment brings up atext box warning the student that submitting an assignment prevents further modification ofthe assignment section. Selecting OK brings up a second warning box which, when OK isselected again, submits the assignment, closes the lab book, and clears the laboratory.

Grading information is placed on the last page of the section. Gases Assignments Pressing the Report button for a gases assignment brings up a text box

warning the student that submitting an assignment prevents further modification of theassignment section. Selecting OK brings up a second warning box which, when OK isselected again, submits the assignment, closes the lab book, and clears the laboratory.Grading information is placed on the last page of the section.


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Titration Assignments Pressing the Report button for a titration assignment brings up a

dialog box which asks the student to enter the concentration or weight percent of theunknown or unknowns that were assigned. A warning is also given about locking out thesection after the assignment has been submitted. Selecting OK brings up a second warning

box which, when OK is selected again, submits the entered values, submits the section notes, pops up a text box with the correct values, closes the lab book, and clears the laboratory. Thecorrect concentrations and/or weight percents, the entered concentrations and/or weight

percents, and grading information is placed on the last page of the section.

Calorimetry Assignments Pressing the Report button for a calorimetry assignment brings upa dialog box, which asks the student to enter the heat of reaction, solution, or combustion orthe heat capacity of the unknown or unknowns that were assigned. Note that it is important to

play close attention to the units that are requested. A warning is also given about locking outthe section after the assignment has been submitted. Selecting OK brings up a secondwarning box which, when OK is selected again, submits the entered values, submits thesection notes, pops up a text box with the correct values, closes the lab book, and clears thelaboratory. The correct values, the entered values, and grading information is placed on thelast page of the section.

Figure 8. The report window for reporting inorganic assignments. Use the Return to Notes button to cancel the submission process.


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Web Options

Overview. This button is the main access point for the web connectivity option of the program.The Virtual ChemLab simulations can be installed in a client/server mode or in astandalone/student mode. In the client/server mode (a typical computer lab installation)electronic assignments and notebook submissions are handled directly through the local areanetwork. In the student mode, there is no direct connection to receive assignments or submitresults and, therefore, the simulations are limited to working locally without electronicassignments. Consequently, paper assignments or exploratory work are the typical applicationsfor a student version. With the Web Options function, a web-based connection can be establishedand configured to enable the exchange of electronic assignments and notebook results without adirect network connection. Some computer lab installations may find this to be the favored modeof operation as well.

The information that is needed to setup web connectivity is (1) a user ID, (2) a password (oftenyour student ID), and (3) the URL for the web connection. This information must be provided bythe instructor or system administrator. Once this information has been obtained, you will thenonly need an active network connection either through a dialup service, cable modem, DSLservice, regular campus access, or any other valid means. Note that a network connection is onlynecessary when updating notebook results and receiving assignments. All other activity in thesimulations can be performed off-line.

Figure 9. The Web Options page used for establishing and configuringweb connectivity. Web connectivity allows for the exchange ofelectronic assignments and notebook results via the internet.


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Shown in Figure 9 is the Web Options page after it has been enabled for web connectivity. Thereare four functions performed on this page: (1) Enable web connectivity, (2) Create local useraccounts by specifying the user ID, password, and URL, (3) Retrieve from and update to theweb, and (4) Delete local user accounts. Descriptions of each button and text field is given

below.

Enable Web Connection. Clicking this button turns on the web connectivity functionality andallows local user accounts to be created (see Create Account below). As shown in Figure 12, theweb connectivity has already been enabled. Once at least one user account has been successfullycreated, the web connectivity functionality cannot be disabled until all local accounts have beendeleted (see Delete below).

Create Account. Because class assignments, notebooks, and grades are unique to each studentregistered in the ChemLab database, a unique account must be created for each user on eachcomputer. Clicking the Create Account button allows a new local user account to be created byentering a valid user ID, password, and URL. There are two important considerations to keep in

mind when creating accounts. First, before any accounts are created, access to the laboratories isimmediate and bypasses the card reader requesting password (student ID) information. The firstaccount can only be created in the lab book using the Create Account button, and subsequententry into the laboratories will require providing the correct password at the card reader. Afterthe first account has been created, new local accounts can be created using the Add New User

button on the card reader. Second, for computer lab installations, each user cannot be guaranteedof using the same computer each time they access the program. Consequently, their local accountwill not always be found on the computer available to them. The Add New User button on thecard reader will be useful to create local accounts as needed when using different computers.

User ID . To create a local account, a valid user ID must be entered in this field. This user ID will be provided by the instructor and is case sensitive. The user ID is typically the first 6 letters ofthe last name followed by the first and middle initials (for example, SmithJD). The entered userID is saved by clicking on the Save button or by pressing Enter or Tab. Using Enter or Tab willautomatically advance the cursor to the password field.

Password. A password is also necessary to create a local account and will be provided by theinstructor. The password is also case sensitive. The password entered here will also be the same

password (usually a student ID) that will be used to enter into the laboratory at the card reader(see Create Account ). The entered password is saved by clicking on the Save button or by

pressing Enter or Tab. Using Enter or Tab will automatically advance the cursor to the URLfield.

URL. The actual web connectivity functionality works by passing assignment and notebookinformation between the student and a central database via a servlet engine running on a webserver at a certain URL address. The exact (case sensitive) URL address that will be used to passassignment and notebook information must be specified in this field. The URL address will be

provided by the instructor. Note that the most recent valid URL address will become the defaultaddress for any subsequent local user accounts; however, each local user may have a uniqueURL address. Also note that most URL addresses will be longer than the length of the text box


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provided. Text at the end of the URL can be accessed by using the arrow keys. Pressing Enter orthe Save button will initiate the account validation process. An internet connection is necessaryin order to validate the user ID and password information.

Enable Automatic Updates. Checking this box will enable automatic updates (both receiving

from and sending to the server) when entering the laboratory at the card reader, exiting alaboratory, and when submitting assignments. This option is recommended when an internetconnection is continuously available. This option is also permanently selected for computer labinstallations using web connectivity.

Send Updates . Clicking on this button will immediately send the notebook and assignmentinformation up to the server where they will be collected by the instructor. This button is the onlylocation where updates can be sent to the server on demand; however, warnings are given toupdate to the server when exiting laboratories and submitting assignments. If the Send Updates

button has been clicked even though there have been no changes made to the notebook, awarning is given indicating that an update is not needed. If an update is still selected (by

clicking Yes at the prompt), then an update will be forced to the server replacing any oldinformation.

Receive Updates . Clicking on this button will immediately collect any new assignments,messages, or grading information posted by the instructor. This button is the only location whereupdates can be received from the server on demand; however, an update can be performedautomatically at the card reader if Enable Automatic Updates has been selected. If the ReceiveUpdates button has been clicked even though there have been no changes made to theinformation on the server, a warning is given indicating that an update is not needed. If an updateis still selected (by clicking Yes at the prompt), then an update will be forced from the serverreplacing any old information stored locally.

Save . Clicking the Save button saves any text entered in the User ID, Password, or URL fields.Clicking Save in the URL box also initiates the account validation process with the server.

Cancel. Clicking the Cancel button cancels the account creation process and resets the WebOptions page back to its initial state. Clicking Cancel does not cancel any web operations thatmay be in progress.

Delete. Clicking on this button deletes the current local account from the local hard drive andreturns the user back to the hallway. Deleting all the local user accounts returns the software

back to the original installed state and disables the web connectivity option. A warning is given before the actual account deletion occurs.

Calorimetry User Guide

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Transcript of Calorimetry User Guide