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CHEM 1314 Lab 1-11

celinahagen

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celinahagen

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Courtney)Baukal)

August)25th,)2014)

Experiment)#01)

The)Determination)of)the)Percent)of)Water)in)a)Compound)

CHEM)1315H)012)

) )

PURPOSE In this experiment, you will test two hygroscopic ionic compounds to determine their water of hydration. Although the water molecules are securely attached to the ionic solid, they are susceptible to removal by heat. You will gently heat a sample of the compound to release the waters of hydration. By measuring the mass of the sample before and after heating, you can determine the amount of water in The sample and calculate its water of hydration. In this experiment, you will: ·)Carefully heat a measured sample of one hygroscopic ionic compounds. ·)Determine the water of hydration of each compound. ·)Complete the chemical formula of each compound. MATERIALS Balance Crucible with cover Crucible tongs Spatula Ring stand Ring Clay triangle Lab burner striker ONE of the following compounds: Magnesium sulfate, MgSO4•nH2O Copper (II) sulfate, CuSO4•nH2O Manganese (II) sulfate, MnSO4•nH2O Sodium carbonate, Na2CO3•nH2O )

PROCEDURE)

1. Obtain and wear goggles for this lab. 2. Set up a ring stand, ring, and wire clay triangle for heating the sample (found in the common cabinets) according to figure 2 above. 3. Measure the mass of a clean, dry crucible with its cover. Place the cover on top of the crucible when weighing. Always wear gloves or use a Kimwipe to touch the crucible, otherwise you will add the weight of any oils from your skin to the mass of your sample. Record this mass to 0.0001 grams in the Before Heating data table below. BALANCE DIRECTIONS ARE LOCATED AT THE BEGINNING OF THE PROCEDURES SECTION. 4. Obtain about 1–1.5 g of the selected hydrate on weighing paper or in a weigh boat. Record the mass to the nearest 0.0001 g in the data table below. Record your hydrate selected on the line above the data table below. Record the color of the hydrate before heating. 5. Place the hydrate in the crucible so that the hydrate is covering the bottom of the crucible. Use a spatula to break up any large pieces of the substance by pressing the pieces against the wall of the crucible. Place the cover on top of the crucible when weighing. Measure and record the mass of the crucible, cover, and compound to 0.0001 g. Record this weight in the Before Heating data table below. 6. Rest the crucible on the clay triangle. Tip the crucible light slightly so that it does not fit snugly on top of the crucible. Do not tip it towards you. ESCAPING GASES DURING HEATING COULD CAUSE HARM. 7. Set up a bunsen burner and ignite the burner away from you and the crucible. Once lit, adjust

the flame until a small flame is produced. Once adjusted, place the burner underneath the crucible. 8. Gently heat the crucible for ten minutes. Depending on the compound, the color of the sample may change significantly as the water of hydration is driven out of the crystals. Record your observations. 9. Once heating is complete, turn off the burner at the gas source. Using a pair of crucible tongs, cover the crucible and allow the sample to cool for about ten minutes. DO NOT WEIGH THE CRUCIBLE UNTIL IT IS COOL TO THE TOUCH. 10. When the crucible is cool enough to handle safely, measure and record the mass of the crucible, cover, and contents. Record this weight to 0.0001 grams in the After Heating data table below. 11. After the 1st weighing, heat the crucible of your sample for ten more minutes. Allow it to cool again completely and measure and record its mass to 0.0001 grams in the After Heating table below in the box labeled 2nd weighing. 12. Write the full names of your sample and its calculated mass on your waste sheets. Dispose of your samples in the solid waste container. 13. Repeat steps 1H12 for trial 2 using a different starting amount of the same hydrate sample used in trial 1. PRE LAB 1. Define a hydrate. Are all hydrates the same? Give specific differences and similarities between two examples of a hydrate. A hydrate is any compound with H2O. No some require stronger concentrations of water due to their polarities and electron orbits. 2. Why is it important to perform more than one trial of this experiment? Be specific. Because it’s extremely easy for there to be an error so multiple trials will reinforce results or show that one of the experiments went completely wrong.)

Courtney Baukal and Duncan Clark

2 September 2014

Experiment 2

The Determination of a Chemical Formula

Chemistry 1315- 085

! Baukal,!Clark!! 1!

Purpose and Techniques:

This experiment will put the law of definite proportions to use; this is also known

as the empirical formula of a compound. The true chemical formula is found through

determining the mass of each item present in a compound. For this specific experiment,

the percent of copper, chlorine, and water in a hydrate was determined.

A lab burner, specifically a Bunsen burner, was used to evaporate the water from

the hydrate. A Bunsen burner is connected to a gas line and a sparker ignites the flame.

The bottom dial may be used to increase or decrease flame size. The burner heats up the

compound. The vacuum was used to purify the copper in the copper chlorine compound.

The vacuum is a tube hooked up to a special faucet on one end and a special flask on the

other. When the water is turned on, a vacuum is created and it sucks the water down

from the filter. Water is run through the filter to take all excess chemicals off the copper

and the suction removes the water so that pure copper is left. The drying oven serves the

same purpose as a normal cooking oven. The drying oven removes any water that was

not removed during the vacuum process.

A chemical formula shows the proportion of atoms in a chemical compound. The

molecular weight of a chemical formula is the weight of the atoms in the compound. To

find this the mass of each element must be found and added together. For example, the

molecular mass of C12H22O11 is 12(mass of C) + 22(mass of H) + 11(mass of

O) molecular mass C12H22O11 = 12(12.01) + 22(1.008) + 11(16.00) = 342.3

(Helmenstine).

Chemicals and Materials Required:


A crucible with a cover, crucible tongs, a spatula, a ring stand, a ring, and a clay

triangle were all used along with the Bunsen burner to evaporate the water from the

hydrate. The compound is an unknown solid copper chloride hydrate; this does not

produce any safety concerns unless it is eaten or gets in an eye. A 50 milliliter (mL)

beaker, a Buchner funnel, filter flask, and filter paper to fit the Buchner funnel are needed

to separate the copper from the compound along with aluminum wire, 95% ethanol

solution, 6 M Hydrochloric acid (HCL), distilled water, a wash bottle, and a glass stirring

rod. These materials make up the vacuum. The 6 M Hydrochloric Acid must be used

with great care; it will burn skin. A watch glass and drying oven were used to finalize the

amount of copper in the compound. The drying oven which is heated to 110 degrees

Celsius must be handle with care like any hot object. All masses were taken using the

balance and were recorded to the 0.001g.

Experimental Procedure:

Set up a ring stand, ring, and clay triangle for heating. Record all data. Measure

the mass of the crucible with its cover. Obtain about one gram of the unknown copper

chloride hydrate using weighing paper. Put compound into the crucible and use the

spatula to break up large pieces; weigh the crucible with the substance in it. Set up

crucible on the clay triangle; ignite the Bunsen burner and make the flame small and blue.

Move the burner slowly back and forth underneath the crucible to gently heat the sample;

do not burn it (the color should change from blue-green to brownish; when the sample

has turned brown, gently heat the crucible for two more minutes). Once finished, turn off

the Bunsen burner and allow the crucible to cool for 10 minutes. Once cooled, measure

the mass of the crucible with the sample inside. Next, transfer the brown solid to a 50mL


beaker. Wash out the crucible with two 8 mL aliquots of distilled water and pour into the

beaker. Stir the liquid and compound with a stirring rod until the copper chloride is

dissolved (the color should be blue-green). Obtain a piece of aluminum wire and coil the

wire loosely around an index and middle finger (preferably with fewer coils).

Completely immerse the wire in the copper chloride solution. When reaction is complete

the solution will be colorless. Add 5 drops of 6 M Hydrochloric Acid to the solution.

Use a glass stirring rod to scrape the copper from the aluminum wire back into the

beaker. Slide the wire up the side of the glass beaker and out of the solution with the

stirring rod; rinse off any remaining copper with distilled water (if the copper will not

come off, wash the wire with a drop or two of HCl). Place rinsed wire on kimwipe.

Collect and wash the copper produced in the reaction. Set up a Büchner funnel for

vacuum filtration. Obtain a piece of filter paper and place it inside the funnel covering all

the holes then wet the filter paper with distilled water. Start the vacuum filtration and

press the filter paper down onto the funnel so that a tight seal is created. Scrape the large

pieces of copper from the reaction onto the filter paper as the solution is placed in the

funnel. Wash all the copper remaining inside the beaker into the funnel with small

amounts of distilled water. Wash the copper twice with distilled water. Turn off the

suction on the vacuum filtration apparatus. Add 10 mL of 95% ethanol to the copper on

the filtration paper and let it sit for a minute. Turn the suction back on and let the

vacuum filtration run for 5 minutes. Measure and record the mass of a watch glass.

Once the filter paper is completely dry, remove it from the funnel and transfer the copper

to the watch glass. Dry the watch glass in the drying oven for 10 – 15 minutes. Remove

from oven using tongs and let the glass cool. When the watch is cool enough, measure


the glass and the copper. Repeat the drying and cooling of the copper until the difference

between the last two weighings are within 0.005g. Dispose of the copper in solid waste

container. Weigh and record the aluminum wire mass then place in electrode waste

container. Dispose the filtered liquid in the bottom of the vacuum flask in the organic

waste container.

Results and Conclusions:

Weighings

Mass of crucible with lid (g) 35.384g

Mass of crucible with lid and hydrated sample (g) 36.407g

Mass of crucible and dehydrated sample (g) 36.178g

Mass of empty watch glass (g) 40.862g

Mass of watch glass and copper 1st weighing (g) 41.219g

Mass of watch glass and copper 2nd weighing (g) 41.217g

Weighing Inferences

Mass of hydrated sample (g) 1.023g

Mass of dehydrated sample (g) 0.794g

Mass of water evolved (g) 0.229g

Moles of water evolved (mol) 0.0127 mol

Mass of copper (g) 0.355g

Moles of copper (mol) 0.00559 mol

Mass of chlorine (g) 0.439g

Moles of chlorine (mol) 0.0124 mol


% copper by weight 35%

% chlorine by weight 43%

% water by weight 22%

The proper chemical formula for the compound tested is Cucl2 �2H2O. The

molecular weight of the copper chloride hydrate is 170.484g/mol. The copper is dry

enough if there is less than a 0.005g difference between a first and second weighings

from 10 – 15 minutes in the drying oven. A different starting mass would have simply

resulted in larger numbers mass and moles to convert into percentages. There may have

been errors in this experiment due to an inability to fully remove all the copper from the

funnel. This experiment exemplified the process of determining molecular formulas. It

also showed how compounds can be broken down.

Sample Calculations:

Mass of hydrated sample = Mass of crucible with lid and hydrated sample – mass of

crucible with lid which was 36.407g – 35.384g = 1.023g. Mass of dehydrated sample =

mass of crucible and dehydrated sample – mass of crucible and lid which was 36.178g –

35.384g = 0.794g. Grams of water = mass of hydrated sample – mass of dehydrated

sample which was 1.023g – 0.794g = 0.229g. Moles of water = grams of water / molar

mass which was 0.229g / (18.0148g/mol) = 0.0127moles. Mass of copper = mass of

watch glass and copper – mass of watch glass which was 41.217g – 40.862g = 0.355g.

Moles of copper = mass of copper / molar mass which is 0.355g / (63.546g/mol) =

0.00559moles. Mass of chlorine = mass of hydrated sample – (mass of water + mass of

copper) which was 1.023g – (0.229g + 0.355g) = 0.439g. Moles of chlorine = mass of

chlorine / molar mass which is 0.439g / (35.453g/mol) = 0.0124moles. Percent of copper


= mass of copper / total mass which is 0.355g / 1.023g = 35%. Percent of water = mass

of water / total mass which is 0.229g / 1.023g = 43%. Percent of chlorine = mass of

chlorine / total mass which is 0.439g / 1.023g = 22%. The proper chemical formula = %

of element / molar mass and then divide all three outcomes from each element by the

largest outcome. Multiply each outcome by however big a number is needed to make all

the outcomes whole numbers. For copper it is 35% / (63.546g/mol) = 0.55. For chlorine

it is 43% / (35.453g/mol) = 1.21. For water it is 22% / (18.016g/mol) = 1.22. Since 1.22

is the largest outcome divide them all by 1.22; so 0.55 / 1.22 ≈ !! and 1.21 / 1.22 ≈ 1 and

1.22 / 1.22 = 1. Since !! is not a whole number, multiply each result by two to make them

all integers. Copper is !! * 2 = 1. Chlorine is 1 * 2 = 2. Water is 1 * 2 = 2. Therefore the

proper chemical formula for the hydrate is Cucl2 �2H2O. Molecular weight = molar

mass of copper + (2 * molar mass of chlorine) + (2 * molar mass of water) which is

63.546g/mol + (2 * 35.453g/mol) + (2 * 18.016g/mol) = 170.484g/mol.

References:

Helmenstine, Anne Marie. "How to Calculate the Empirical and Molecular

Formula of a Compound." About.com. About.com. Web. 3 Sept. 2014.

<http://chemistry.about.com/od/workedchemistryproblems/a/How-To-Calculate-

The-Empirical-And-Molecular-Formula-Of-A-Compound.htm>.

Courtney Baukal

9 September 2014

Experiment #3

Determining Avogadro’s Number

Chemistry 1315 – 085

Baukal& 1&

Purposes and Techniques:

The purpose of this lab is to prove Avagadro’s number, which is the number of

atoms in a mole. It is a type of recreation of Robert Millikan’s experiment. So

theoretically, 6.022 x 1023 atoms per mole should be discovered.

LabQuest was used in this experiment to record the current produced by the

Current Probe. The Vernier Current Probe and then DC power source sent an electrical

current to the electrodes. The analytical balance was used to weigh the mass of the

copper; it was recorded to the 0.001 gram.

A coulomb (C) is a unit charge that is equal to 6.421 x 1018 electrons. The

number of coulombs = the number of amperes (amps) * number of seconds (s)

(“Coulomb”). Percent error = actual yield / theoretical yield. The percent error should be

used in all experiments possible to determine how close the test was to what the results

should have been. The error is how far off the results are from the theoretical yield.


A copper strip acted as the anode and zinc strip was the cathode. The copper was

cleaned with sandpaper while the zinc was cleaned with steal wool. The 1M sulfuric

acid(H2SO4), which was used to immerse the electrodes, must be handled with great care;

it can cause painful burns if it comes into contact with skin. The H2SO4 filled a

250millimeter beaker ¾ full. A Vernier Current Probe and a 1.5volt DC were connected

with 2 connecting wires with alligator clips to bring a current to the electrodes and a ohm

resistor was also used. The current was recorded using LabQuest. Distilled water was

used to clean the electrodes during each trial.


Baukal& 2&

Use a piece of sandpaper to clean a strip of copper (the anode of the

electrochemical cell) and clean a strip of zinc (the cathode) with steel wool. Measure the

mass of copper. Record all measurements throughout the experiment. Fill a 250milliliter

(mL) beaker ¾ full with 1 Molar (M) sulfuric acid (H2SO4). Obtain a DC power supply,

an ohm resistor, a Vernier Current Probe, and two connecting wires. Connect the copper

electrode to the black lead on the Vernier Current Probe. Connect the power supply ti the

red lead on the Vernier Current Probe. Connect the power supply to the black lead on the

ohm resistor. Connect the zinc to the red ohm resistor. Connect the Current Probe to

LabQuest and create a new file. The data-collection rate should be set to .2

samples/second, interval 5 seconds/sample, and the duration to 180 seconds. Pull up the

graph and plug in the DC power supply. Place the electrodes into the 1 M H2SO4 solution

and make sure the electrodes are immersed at equal depths and as fart apart as possible.

The initial current should be 0.2 to 0.6amp range. Adjust the settings on the ohm resistor

if the current is not in that range. Start data collections once current is set. Observe the

reaction carefully and immediately unplug the power supply once the data collection has

stopped. Then carefully remove the electrodes from the H2SO4 solution. Rinse the

copper and zinc electrodes with distilled water into a separate beaker ad dry the copper

electrode very carefully. Measure and record the mass of the copper. Determine the

average current applied during the experiment using LabQuest. Then repeat the

experiment for a second and third trial. Observe the color of the acid after the third trial.

References:

"Coulomb." Wikipedia. Wikimedia Foundation, 9 Jan. 2014. Web. 8 Sept.

2014. <http://en.wikipedia.org/wiki/Coulomb>.


15 September 2014

Experiment 4

Determining the Mole Ratios in a Chemical Reaction

Chemistry 1315 – 085

Baukal,'Clark' 1'


This experiment exemplified how to find mole ratios. The purpose of this

experiment is to show the complete reaction between sodium hydroxide, sodium

thiosulfate, and sodium hypochlorite. The reaction should produce 4NaClO+Na2S2O3

+ 2NaOH = 4NaCl + 2Na2SO4 + H2O.

LabQuest was connected to a Temperature.Probe to read the temperature more

accurately as the reaction is completed.

Exothermic reactions release energy; endothermic reactions absorb the energy in

the form of heat. A bond being formed is endothermic since it requires energy and a bond

being broken is exothermic since it gives off energy. A limiting reagent is the reactant

that is completely used up. The left over is the excess reactant and there should not be

any limiting reagent left.


LabQuest and the Temperature Probe were used to record the temperature change

during the reaction. Two 10milliliter (mL), 2 25mL, and 2 50mL graduated cylinders

along with 2 250mL and one 600mL beakers were used to measure out the solutions of

0.9M sodium hypochlorite and 0.5 M sodium thiosulfate. Sodium hypochlorite, bleach,

may stain clothes. The reaction took place in a Styrofoam cup.


Connect the Temperature Probe to LabQuest and set up the graph. Put 200

milliliter (mL) of sodium thiosulfate (Na2S2O3)'in'a'250mL'beaker;'place'400mL'of'

sodium'hypochlorite'(NaOCl),'bleach,'in'a'600mL'beaker.''Pour'25mL'of'0.5M'NaOCl'

into'a'Styrofoam'cup.''Immerse'the'tip'of'the'Temperature'Probe'into'the'NaOCl'in'

Baukal,'Clark' 2'

the'Styrofoam'cup.''Measure'out'25mL'of'0.5M'Na2S2O3.''Start'the'data'collection'

and'read'a'few'initial'temperatures'then'add'the'Na2S2O3'and'swirl'the'Styrofoam'

cup'to'mix'the'reactants.''Stop'the'data'collection'once'the'temperature'readings'

stop'changings.''Record'the'maximum'temperature'change.''Dispose'of'the'mixture.''

Continue'repeating'the'trial'with'the'different'volumes'of'solutions'stated'in'the'

data'table.'

Results'and'Conclusions:'

Data'Table'1'

Volume OCl– (mL)

Volume S2O32–

(mL) Temperature change (°C)

25 mL (Step 4)

25 mL (Step 4)

27.2

27 mL 23 mL 30.6

30 mL 20 mL 33.9

32 mL 18 mL 35.4

35 mL 15 mL 38.9

37 mL 13 mL 33

40 mL 10 mL 27.3

42 mL 8 mL 21.1

45 mL 5 mL 8

47 mL 3 mL 7.1

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Baukal,'Clark' 3'

Data'Table'2'

Volume OCl– (mL)

Moles of OCl-

Volume S2O32–

(mL) Moles of

S2O32-

Mole Ratio OCl-/S2O3

2-

25 mL

0.0225 moles 25 mL

0.025 moles 0.9

27 mL 0.0243 moles 23 mL 0.023 moles 1.0565

30 mL 0.027 moles 20 mL 0.02 moles 1.35

32 mL 0.0288 moles 18 mL 0.018 moles 1.6

35 mL 0.0315 moles 15 mL 0.015 moles 2.1

37 mL 0.0333 moles 13 mL 0.013 moles 2.5615

40 mL 0.036 moles 10 mL 0.01 moles 3.6

42 mL 0.0378 moles 8 mL 0.008 moles 4.725

45 mL 0.0405 moles 5 mL 0.005 moles 8.1

47 mL 0.0423 moles 3 mL 0.003 moles 14.1

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Baukal,'Clark' 4'

Graph'1'

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' The'experimentally'determined'mole'ratio'of'the'balanced'equation'is'2.1'

moles'of'OClS'to'1'mole'of'S2O32S;'this'is'the'result'because'there'was'the'largest'

temperature'change'at'this'ratio'and'therefore'this'reaction'was'the'most'complete.''

The'original'experiment'was'supposed'to'have'equal'molarities'for'the'solutions.''

This'is'obviously'not'necessary'since'the'molarities'were'not'equal'for'this'

experiment.''Ratios'can'be'calculated'no'matter'what'the'difference'between'the'

molarities'is.''Sodium'hypochlorite'was'the'limiting'solution'until'the'peak'reaction'

(35mL'of'sodium'hypochlorite'with'15mL'of'sodium'thiosulfate);'after'that'point,'

sodium'thiosulfate'was'the'limiting'solution.''Our'determined'mole'ratio'does'not'

match'the'balanced'equation'(4NaClO+Na2S2O3 + 2NaOH = 4NaCl + 2Na2SO4 +

H2O); our mole ratio is 1.6 : 1, but it should be 2 : 1 (ClO- : S2O32-). This is most likely

due to inaccurate measurements of mL of each solution. A more accurate ratio could

0'

5'

10'

15'

20'

25'

30'

35'

40'

45'

0.9' 1.056' 1.35' 1.6' 2.1' 2.5615' 3.6' 4.725' 8.1' 14.2'

temperature'change'(°C)''

Mole'Ratio'

mole'ratio'vs.'temperature'change'(°C)'

Baukal,'Clark' 5'

have been discovered if the incremental changes in the amount of each solution were

smaller.

Sample'Calculations:'

' Moles'of'OClS'='liters'*'molarity.''Moles'of'S2O32S'='liters'*'molarity'*'2.'

References:'

Kent. "Endothermic and Exothermic Processes." Endothermic and

Exothermic Processes. Web. 15 Sept. 2014.

<http://www.kentchemistry.com/links/Matter/EndoExo.htm>.

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23 September 2013

Experiment #5

Separation and Qualitative Analysis of Cations

Chem 1315 – 085

Baukal,'Clark' 1'


The objective of this lab was to discover anions and cations in an unknown

solution. It is also an introduction to precipitates.

A hot plate was used to heat up the tubes during a few tests; it was set to level 9.

Heat contributes to certain reactions and caution must be used whenever heat is involved

to avoid burns.

The centrifuge was used to separate the precipitate and the supernatant. It was

run for about 30 seconds each time. The most important thing to remember with this

instrument was balancing it with a blank.

A precipitate is the solid that forms from a reaction and the supernatant is the

liquid produced (Precipitation Reactions).

AgNO3'+'HCl'!'HNO3'+'AgCl'

' Pb(NO3)2'+'H2SO4'!'PbSO4'+'2HNO3


A tube rack was utilized and a tube holder was used for the hot water baths. The

hot plate was set to level 9; caution was used since it can cause burns when touched with

bare skin. 6M hydrochloric acid (HCl), 6M sulfuric acid (H2SO4), and 6 M nitric acid

(HNO3) should be used with caution since it can burn skin. Distilled water was used for

multiple purposes. Blue and red litmus paper was used to test pH. 3% hydrogen

peroxide(H2O2), 6 M ammonia (NH3),sodium hydroxide (NaOH), potassium nitrite

(KNO2), potassium thiocyanate (KSCN), and potassium ferrocyanide (K4[Fe(CN)6]')

were used as a testing agents. Pipets were used to transfer drops and many solutions

were centrifuged.

Baukal,'Clark' 2'


Set up 10 test tubes and a hot water bath. Three drops of each of the 10 cations

along with 8 drops of HCl will be in test tube 1. A white precipitate should form,

showing the presence of Ag+,'Pb2+,'and/or'Hg22+.''Centrifuge'the'test'tube'and'add'one'

more'drop'of'HCl;'continue'this'until'no'more'precipitate'forms.''Centrifuge'the'

mixture'and'transfer'the'supernatant'liquid'to'test'tube'4.''Use'1'mL'of'distilled'

water'and'centrifuge'test'tube'1,'then'pour'out'the'water.''Again'add'1mL'of'water'

to'tube'1'and'place'in'the'water'bath'for'3'minutes.''Centrifuge'the'liquid'and'decant'

it'into'test'tube'2.''Add'5mL'of'H2SO4'to'test'tube'2;'a'white'precipitate'will'form'if'

Pb2+'is'present.''Add'1'mL'of'NH3'to'tube'1;'if'a'dark'gray'precipitate'forms'then'

Hg2+'is'present.''Centrifuge'and'pour'into'tube'3;'dispose'of'the'precipitate.''

Centrifuge'and'decant'after'each'step.''Add'15'drops'of'6'M'HCl'to'tube'3'and'stir.''

Test'for'pH'with'litmus'paper'and'continue'adding'HCl'until'it'is'acidic.''If'a'white'

precipitate'forms,'Ag+'is present.

Add 10 drops of hydrogen peroxide to tube 4 and check for pH with red litmus

paper; repeat until basic. Once basic, add 3 drops of NaOH then stir and place in water

bath; the darker precipitate, the higher the concentration of ions. Decant to tube 10. Add

10 drops of distilled water to tube 4 then centrifuge it and dispose of the supernatant.

Then, add 5 drops of water to tube 4 and H2SO4 , testing with blue litmus paper until the

solution is acidic. Centrifuge and transfer supernatant to tube 5. Add 10 drops of water

to tube 4; centrifuge; discard supernatant. Add 1 mL or water, H2SO4, ad H2O2 to tube 4

and place in the water bath, then pour half the solution into tube 6 and add 1mL of HNO3

along with a small scoop of NaBiO3. Centrifuge; if the liquid is purple, Mn2+ is present.

Baukal,'Clark' 3'

Add KNO2 to tube 4; if a yellow precipitate forms, Co2+ is present. Add NH3 to tube 5

until it is basic and then add one more mL of NH3. Centrifuge; if the solution is blue,

Cu2+ is present. Add 10 mL of water and then add H2SO4 until precipitate dissolves;

transfer half to tube 8. Add 5 drops of KSCN to tube 5; if the solution is red than Fe3+ is

present. Add 2 drops of HCL to tube 8 and prepare a beaker with 75 mL of water. Add a

few drops of the solution to the water; if white cloudiness appears then Bi3+ is present.

Add 10 drops of HNO3 to tube 10 and continue adding until solution is acidic.

Add NH3 until solution is basic and then add 3 more drops. Centrifuge; if there is a

precipitate, Al3+ is present. Transfer supernatant to tube 9. Add HCl until tube 9 is

acidic. Then add 3 drops of K4[Fe(CN)6], then centrifuge. If there is a precipitate, Zn2+

is present. Dispose of all materials.


Results Table with Unknown #5

Known Solution Unknown Solution

Test Ions Tested Results Results Conclusions

1a Pb2+, Hg22+, Ag+

White precipitate with a cloudy, yellow supernatant

White precipitate with a pink supernatant

Yes

1b Pb2+ Very cloudy, white White precipitate Yes

1c Hg22+ Dark gray precipitate No dark gray

precipitate No

1d Ag+ White precipitate formed and then quickly disappeared

No precipitate No

Baukal,'Clark' 4'

2a Mn2+ Purple supernatant

Brown precipitate and clear supernatant

No

2b Co2+ Yellow precipitate

Light yellow supernatant with a yellow and a brown precipitate

Yes

2c Cu2+ Blue supernatant No blue supernatant No

2d Fe3+ Red supernatant No red supernatant No

2e Bi3+ White and murkey No white supernatant No

3a Al3+ Gray/brownish precipitate

Clear supernatant No

3b Zn2+ Green precipitate Blue/green precipitate Yes

A cation has a positive charge and gains electrons while an anion has a negative

charge and loses electrons. The number of electrons an element has determines its

charge. The charges on many metals varies while for most other elements the charge is

determined by its placement on the periodic table of elements.


References:

"Precipitation Reactions." - Chemwiki. Web. 23 Sept. 2014.

<http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Reactions_in_Aq

ueous_Solutions/Precipitation_Reactions>

Baukal,'Clark' 5'


7 October 2014

Experiment #6

The Synthesis of Alum

Chem 1315-085

Baukal,'Clark' 1'


The purpose of this experiment was to exemplify the process of forming an alum.

It also showed an exothermic reaction.

A synthesis reaction is when two or more lone elements combine to form a

complex product. The molecular weight for KAl(SO4)2 • 12H2O is [39.098 + 26.982 +

2(32.066 + (4 * 15.999))] + 12[(2* 1.0079) + 15.999] which equals 474.3816.

A Buchner funnel and a filter flask system were hooked up to water and then

suction was created to separate solids and liquids. The hot plate was used with caution as

well as an ice bath to control the temperature of the experiment. The balance measured

the weight to the nearest 0.001 grams.


Potassium hydroxide (3M KOH) solution is caustic; avoid contact with skin and

clothing. 3M sulfuric acid (H2SO4) can cause painful burns. About one gram of

aluminum foil was used. Set the hot plate at 7. Aqueous ethanol solution (50%) was

used to clean the crystals.


Tear about one gram of aluminum foil into small pieces after setting up a Buchner

funnel. Add 5 milliliters (mL) at a time to the beaker of aluminum foil; swirl the mixture

for 5 minutes after each reaction. Pour the reaction through the Buchner funnel; rinse the

beaker with water and put filtered liquid into the beaker. Use an ice bath to cool the

mixture to room temperature. Afterwards, add 35 mL of sulfuric acid to the beaker while

stirring. If there are any solids left, separate it using the Buchner funnel. Boil the

mixture until there is 40 mL left in the beaker, then place in an ice bath for 20 minutes.

Baukal,'Clark' 2'

Scrape the bottom of the beaker if no crystals form. Repeat heating and cooling if

crystals still don’t form. Pour the solution through the funnel to collect the crystals; rinse

the crystals with 50 mL of ethanol. Lastly, dry the crystals and weigh. Repeat the trial.


Mass Analysis

Trial 1 Trial 2

Mass of aluminum foil 0.717g 0.935g

Mass of aluminum product

8.350g 9.835g

The theoretical yield for trial 1 is 6.859g; for trial 2 it is 8.944g. The percent

yield for trial 1 is 121.74% and for trial 2 it is 109.96%. The overabundance is due to

excess water on the alum crystals. The equations for this experiment is as follows: part 1

2Al + 2OH- + 6H2O ⇒ 2Al(OH4)- + 3H2, part 2 [Al(OH)4]- + H+ ⇒ Al(OH)3 + H2O, part

3 Al(OH)3 + 3H+ + 3H2O ⇒ [Al(H2O)6]3+, part 4 [Al(H2O)6]3+ + 2SO42- + K+ +6H2O ⇒

KAl(SO4)2 • 12H2O.


To get the theoretical yield: mass of aluminum +[ !"##!!"!!"#$%&#$!(!)! ∗

!!!"#!!"!!"!".!"#!!!!"!!" *

!!!"#$%!!"!!"!!!!"#$!!"!!" ∗ !".!"!!!"!!"!!!!"#!!"!!"! = mass of sulfate] + [!"##!!"!!"#$%&#$(!)! ∗

! !!!"#!!"!!"!".!"#!!!!"!!"! ∗

!!!"#!!"!!!!!"#!!"!!" ∗

!".!!!!!"!!!!!"#!!"!! = mass of potassium] = theoretical yield. Percent

yield = (actual yield / theoretical yield) * 100.

References:

Helmenstine, Anne Marie. "What Is a Synthesis Reaction in Chemistry?" About. Web. 6

Baukal,'Clark' 3'

Oct. 2014. <http://chemistry.about.com/od/chemicalreactions/a/synthesis-

reaction.htm>.

Courtney Baukal

14 October 2014

Experiment #7

Determining Enthalpy of a Chemical Reaction

Chem 1315-085

Baukal 1"


This experiment will exemplify how enthalapies of formation are discovered; it

proves Hess’s law. Ideally the experiment will have the same outputs calculated in the

pre-lab activity.

The temperature probe records the temperatures of the reaction on LabQuest. The

[x,y] icon shows the values once the collections are completed.

NaOH + HCl ⇒ H2O + NaCl [(-411.2 + -285.8) – (-425.8 + -92.3) = -178.9] the

enthalpy of formation for this reaction is -178.9. NaOH + NH4Cl ⇒ NaCl + NH3 + H2O

[(-411.2 + -80.29 + -285.8) – (-425.8 + -314.4) = -37.09] the enthalpy of formation for

this reaction is -37.09. HCl + NH3 ⇒ NH4Cl [-314.4 – (-92.3 + -80.29)] the enthalpy of

formation for this reaction is 80.29.

Chemical and Materials Required:

120 milliliters (mL) of 2.0M sodium hydroxide (NaOH), 120 mL of 2.0M

hydrochloric acid (HCl), and 60 mL of ammonia (NH3) were used with caution. A

Styrofoam cup contained the reaction.


Put a Styrofoam cup in a beaker and pour 50mL of HCl into it; put the

temperature probe in the solution. Start recording temperatures and then add 50mL of

NaOH while swirling the solution. Record the initial and maximum temperature. Repeat

the same steps except start with 50mL of NaOH then add 50mL of NH4Cl. Repeat a third

time but with 50mL of HCl then add 60mL of NH3.

Baukal 2"


Data Table

Reaction 1 Reaction 2 Reaction 3

Maximum temperature (°C) 30.2 18.9 30.8

Initial temperature (°C) 17.0 18.1 18.0

Temperature change ∆T (°C) 13.2 0.8 11.2

Heat energy q (kJ) -5.683kJ -0.344kJ -4.822kJ

Enthalpy Change ∆H (kJ/mol) -56.83 -3.44 -48.22

The experimental molar enthalpy is -54.39 kJ/mol, which is not the same as the

experimentally calculated value. The theoretical ∆H"of"reaction"3"is"80.29;"the"percent"

error"is"60.06%.""The"percent"error"for"the"experimental"molar"enthalpy"is"67.74%.

There was a larger percent error for the calculated value for reaction 3, although,

logically the experimental molar enthalpy value should be further off since it has more

steps ad therefore more room for error. This experimental process does support Hess’s

law since the answers were relatively close to the same percent error. Sources of error

most likely came from not mixing the reaction well enough to get the peak temperature.

A bomb calorimeter could have made the experiment more successful since Styrofoam

cups are not very advanced.


q(kJ) = [mL of solution * 1.03g/mL * 4.18 J/g ⋅°C"*"(final"temperature"–"initial"

temperature)]/1000J.""∆H"="q"/"(molarity"*"liters)."Experimental"molar"enthalpy"="

reaction"1"–"reaction"2."Percent"error"="(experimental"value/"theoretical"value)"*"

100."

Baukal,'Clark'

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'

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'

'

'

Courtney'Baukal'and'Duncan'Clark'

21'October'2014'

Experiment'#8'

Exploring'the'properties'of'Gases'

Chem'1315F085'

' '

Baukal,'Clark' 1'

Purpose(and(Techniques:(

' This'lab'is'used'to'exemplify'the'properties'of'gases.''PV=nRT'is'the'primary'

equation'examined(P=pressure,'V=volume,'n='number'of'moles,''R='ideal'gas'

constant,'T=temperature).'

Lab'quest''record'the'data'collected'by'the'gas'pressure'sensor'and'the'

temperature'sensor.''The'hot'plate'heats'up'the'solution'for'the'hot'water'bath.'

Chemicals(and(Materials(Required:(

' LabQuest,'a'temperature'probe,'and'a'gas'pressure'sensor'are'all'used'to'

observe'the'properties'of'gases.''Rubber'stoppers'are'used'for'airtight'seals'along'

with'LuerFlock'connectors.''A'hot'plate'(used'with'caution)'and'ice'created'different'

temperatures'to'observe'a'relationship'between'pressure'and'temperature.'

Procedure:(

' Connect'the'syringe'with'10mL'of'air'in'it'to'the'Gas'Pressure'sensor;'set'the'

sensor'up'on'LabQuest.''Get'6'different'data'points'of'the'pressure.''Have'5mL'of'air'

in'the'syringe'and'isolate'the'gas'in'the'flask'for'another'set'of'data.''Connect'the'

temperature'sensor'and'set'up'a'heat'bath'with'the'Erlenmeyer'flask;'collect'the'

data'of'different'pressures'at'different'temperatures.''Set'up'the'flask'with'a'cold'

water'bath'and'collect'the'data'of'pressures'and'temperatures.'

'

'

'

'

'

Baukal,'Clark' 2'

Results(and(Conclusions:(

Table'1'

Volume (mL) Pressure (kPa) 10mL 94.74kPa 9mL 109.10kPa 8mL 116.70kPa 7mL 136.7kPa 6mL 155.34kPa 5mL 176.6kPa 4mL 216.26kPa 3mL 224.67kPa

Table'2'

Molecules Pressure (kPa)

0 97.6

5 101.35

7.5 103.7

10 104.25

12.5 106.79

15 108.55

17.5 110.00

20 112.94

22.5 113.00

25 113.50

'

'

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'

Baukal,'Clark' 3'

Table'3'

Pressure (kPa) Temperature (K)

97.55 294.2

98.87 303

99.85 308

100.89 313

102.12 318

103.14 323

104.15 328

Table'4'(hot'water'bath)'

Pressure'(kPa)' Volume'(mL)' Temperature'(K)'

97.13' 5' 302'

97.99' 5' 305'

99.4' 5' 310'

100.12' 5' 312.5'

100.89' 5' 315'

102.24' 5' 320'

103.74' 5' 325'

Table'5'(cold'water'bath)'

Pressure (kPa) Volume (mL) Temperature (K) 90 5 268.7

'

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Baukal,'Clark' 4'

Table'6'

'

'

'

'

0'

50'

100'

150'

200'

250'

3' 4' 5' 6' 7' 8' 9' 10'

Pressure(in(kPa(

Volume(in(mL(

Table(1(

Part Volume

Erlenmeyer flask 125mL

Stopper and Valves Attached to LabQuest 5mL

Original Volume in Syringe 5mL

Baukal,'Clark' 5'

'

'

85'

90'

95'

100'

105'

110'

115'

0' 5' 7.5' 10' 12.5' 15' 17.5' 20' 22.5' 25'

Pressure(in(kPa(

Molecules(

Table(2(

270'

280'

290'

300'

310'

320'

330'

340'

97.55' 98.87' 99.85' 100.89' 102.12' 103.14' 104.15'

Temperature(in(K(

Pressure(in(kPa(

Table(3(

Baukal,'Clark' 6'

'

Volume'and'pressure'are'inversely'related'(P='k/V).''Number'of'molecules'

and'pressure'are'directly'related'(P'='n'*'k).''Pressure'and'temperature'are'directly'

related'(P='k'*'T).''For'pressure'and'volume,'k'is'999.46.''For'pressure'and'

molecules,'k'is'7.94.''For'pressure'and'temperature,'k'is'0.323.''PV'='nkT'which'is'an'

extremely'common'equation'so'I'didn’t'need'to'do'any'math'but'looking'at'the'

relationships'between'pressure'and'the'other'factors'show'this'as'well.''There'were'

many'sources'of'error.''For'example,'table'5'with'the'coldFwater'bath'did'not'work'

at'all.''For'table'4,'the'volume'on'the'syringe'was'supposed'to'change'but'the'

friction'was'too'high'on'the'stopper'for'it'to'move.'''

Sample(Calculations:(

' For'directly'related,'k'='(total'P/number'of'samples)'/'(molecules'or'

temperature'/'number'of'samples).''For'inversely'related,'k'='(total'P/number'of'

samples)'*'(volume'/'number'of'samples).'''

(

92'

94'

96'

98'

100'

102'

104'

106'

302' 305' 310' 312.5' 315' 320' 325'

Pressure(in(kPa(

Temperature(in(K(

Table(4(

!

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!

!

Courtney!Baukal!and!Duncan!Clark!

28!October!2014!

Experiment!#9!

The!Molar!Mass!of!a!Volatile!Liquid!

Chem!1315I085!

!

! !

Baukal,!Clark! 1!


! The!purpose!of!this!lab!is!to!identify!an!unknown,!volatile!liquid.!!The!weight!

of!the!condensed!liquid!and!molar!mass!will!be!used!to!identify!the!substance.!

! The!hot!plate!must!be!used!with!caution;!don’t!touch!it!and!be!careful!with!

changing!the!temperature!of!the!glassware!used!on!it.!!The!lab!quest!and!

temperature!probe!will!record!the!temperature!readings.!

Unknown Compound Molecular Weight

Methyl Alcohol 12.01(C)+4*1.008(H)+16(O)=

32.042g/mol

Ethanol 2*12.01(C)+6*1.008(H)+16(O)=

46.068g/mol

Acetone 3*12.01(C)+6*1.008(H)+16(O)=

58.078g/mol

Isopropyl Alcohol 3*12.01(C)+8*1.008(H)+16(O)=

60.094g/mol

Cyclohexane 6*12.01(C)+12*1.008(H)=

84.156g/mol

Ethyl Acetate 4*12.01(C)+8*1.008(H)+2*16(O)=

88.104g/mol

! The!density!of!water!is!999.7!kg/m3!or!0.9997!g/cm3.!

Materials(Required:(

! A!ring!stand,!hot!plate,!temperature!probe!and!clamps!were!used!for!heating.!!

The!hot!plate!was!set!to!10!and!an!ice!bath!was!used!as!well.!!Lab!quest!and!the!

temperature!probe!were!required!to!record!temperatures.!!A!balance!recorded!the!

Baukal,!Clark! 2!

weights!to!the!nearest!0.001g.!!An!unknown!liquid!was!tested.!!Aluminum!covered!

the!top!of!the!test!tube.!!

Procedure:(

! Record!the!temperature!of!the!room.!!Set!up!a!hot!water!bath!with!a!1000mL!

beaker.!!Immerse!the!temperature!probe!but!do!not!let!it!touch!the!glass.!!Set!up!an!

ice!bath!with!a!600mL!beaker.!!Place!aluminum!foil!over!an!18!X!150mm!test!tube;!

make!two!small!holes!and!place!inside!to!1000mL!beaker!and!weigh.!!Pour!5mL!of!

the!unknown!volatile!liquid!into!the!test!tube.!!Once!the!hot!water!bath!has!reached!

85!degrees!Celsius,!submerge!the!test!tube!in!it!as!far!as!possible.!!Boil!for!10!

minutes!at!98!degrees!Celsius!then!quickly!transfer!the!tube!into!the!ice!bath!and!let!

it!cool!for!a!minute;!remove!and!dry!the!test!tube.!!Measure!the!mass!of!the!test!tube!

in!the!beaker!again.!!Clean!the!test!tube!and!reweigh!it!without!the!unknown.!


Table!1!

Unknown __F__ Trial 1 Trial 2

1 Mass of 100 mL beaker, test tube, and foil cover (g) 69.710g 69.841g

2 Temperature of water bath (ºC) 98 98.3

3 Mass of 100 mL beaker, test tube, foil, and gas sample (g) 69.81g 69.870g

4 Barometric pressure (kPa) 975hPa 975hPa

5 Mass of 100 mL beaker, test tube, foil, and water (g) 98.334g 97.398g

Room!temp!19.5!degrees!Celsius!

The!mass!of!the!gas!for!trial!one!is!0.100!grams;!for!trial!two,!it!is!0.029!

grams.!!For!trial!one,!the!volume!of!the!test!tube!is!0.0286!liters!and!for!trial!two!it!is!

0.0276!liters.!!The!number!of!moles!is!0.0090!for!trial!one;!there!are!0.0087!moles.!!

Baukal,!Clark! 3!

The!molar!mass!found!for!trial!one!is!11.11!g/mol!and!for!trial!two!it!is!3.33!g/mol.!!

These!molar!masses!are!not!similar!to!any!of!the!molar!masses!in!the!unknown!table!

but!it!is!closest!to!methyl!alcohol.!!The!percent!error!is!65.3%!in!trial!one!and!89.6%!

in!trail!two.!!The!gas!did!not!behave!ideally!because!the!number!of!moles!appears!to!

be!very!off.!!I!think!this!gas!actually!had!less!moles!than!were!reported.!!A!lower!

number!of!moles!would!have!reported!a!higher!molar!mass!with!the!grams!

calculated.!!Gases!in!a!smaller!space!tend!to!not!behave!ideally.!!If!the!gas!had!not!

condensed!to!liquid!the!gas!would!have!been!lighter!and!would!have!yielded!a!lower!

mass!than!was!weighed.!!If!a!higher!initial!amount!of!unknown!had!been!used!than!

the!mass!would!have!been!greater!and!would!have!yielded!a!higher!molar!mass!

since!the!other!factors!in!PV=nRT!would!not!have!been!affected.!

Calculations:(

Mass!of!sample!=!mass!in!row!3!–!mass!in!row!1.!!To!find!the!mas!of!the!

water,!subtract!the!mass!in!row!5!from!the!mass!in!row!1.!!To!calculate!the!volume!

of!the!test!tube,!!"##!!"!!"#$% ! ∗ !!!!"!!"!"#!!.!!!"!! ∗ !.!!"!"#$%&!!"!!"#$% .!!!To!get!the!pressure!in!

atm!multiply!row!4!by!0.00987!(1kPa!=!.00987atm).!!For!number!of!moles!

!"#$$%"# !"# ∗!"#$%&!!"!!"#!!!"#$(!)!.!"#!$ !"#$%!!"#!!"#$%&#% ∗!"#$"%&!'%"!!"!!"#$%!(!).!!!To!get!the!molar!mass!take!the!mass!

of!the!vapor!divided!by!the!number!of!moles!founded.!!Percent!error!=!(actual!molar!

mass!I!tested!molar!mass)/!actual!molar!mass.!

References:(

Helmenstine,!Anne!Maria.!"What!Is!the!Density!of!Water?"!About.!About.com,!30!Sept.!2014.!!

Web.!27!Oct.!2014.!<http://chemistry.about.com/od/waterchemistry/f/WhatIIsI

TheIDensityIOfIWater.htm>.!

Baukal,!Clark! 4!

Senese,!Fred.!"Under!What!Conditions!Do!Real!Gases!Behave!Ideally?"!General,,

Chemistry,Online:,FAQ:,Gases:.!Web.!30!Oct.!2014.!

<http://antoine.frostburg.edu/chem/senese/101/gases/faq/realIvsIidealI

conditions.shtml>.!

(

!

!

!

!

!

!

!

!

!

Courtney!Baukal!

4!November!2014!

Experiment!#10!

Vapor!Pressure!and!Heat!of!Vaporization!

Chem!1315E085!

! !

Purposes(and(Techniques:(

The!purpose!of!this!experiment!is!to!analyze!the!effects!of!temperature!on!

pressure.!!An!inverse!relationship!will!be!expected.!

! A!hot!plate!was!used!to!warm!up!water!so!that!the!temperature!could!change!

and!effects!of!temperature!on!pressure!could!be!analyzed.!!The!pressure!and!

temperature!sensors!were!connected!to!the!LabQuest,!which!recorded!these!

changes.!!!

! In!the!equation,!y!=!lnPvap!,!m!=!Edelta!Hvap!/R,!x!=!1/Tk,!and!b=!C.!


( The!ethanol!is!flammable!and!poisonous;!it!should!not!contact!skin!or!

clothing.!!Set!the!hot!plate!to!level!8;!be!cautious!when!adding!or!removing!

glassware!so!that!it!does!not!break!from!the!heat!change.!!LabQuest,!a!temperature!

probe,!and!a!gas!pressure!sensor!recorded!data.!!A!rubber!stopper,!plastic!tubing,!

and!a!syringe!were!used!to!connect!the!experiment!to!the!sensors.!

Procedure:(

! Heat!up!200mL!of!water!in!a!400mL!beaker.!!Connect!the!tubing!to!the!gas!

pressure!sensor!and!put!the!white!stopper!in!a!125mL!Erlenmeyer!flask!with!the!

valve!open.!!Connect!the!gas!sensor!and!temperature!sensor!to!LabQuest;!set!the!

graph!to!record!in!degrees!Celsius!and!kPa.!!Set!up!the!temperature!probe!on!a!ring!

stand!with!the!flask.!!Record!the!temperature!of!the!air!in!the!room!and!the!pressure!

of!the!flask;!start!the!data!collection.!!Fill!a!liter!beaker!with!950mL!or!room!

temperature!water;!secure!the!flask!in!the!beaker!with!the!threeEfinger!clamp.!Stop!

the!data!collection!once!stabilized.!!Record!the!last!data!points.!!Place!the!

temperature!probe!in!the!water!bath!along!with!the!flask.!!Hold!the!flask!down!with!

the!clamp!and!close!the!valve!on!the!stopper!after!30!seconds.!!Thread!a!syringe!

with!3mL!of!ethanol!onto!the!valve!of!the!stopper.!!Inject!the!ethanol!and!then!

quickly!draw!back!the!syringe!to!3mL!and!remove!the!syringe.!!Stir!the!water!bath.!!

Collect!data!and!pressure!and!record!the!last!values.!!For!trial!2!add!enough!hot!

water!to!warm!the!water!bath!by!3!or!5!degrees!and!record!new!temperature!and!

pressure.!!Repeat!adding!water!and!warming!three!more!times.!

References:(

!

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!

!

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!

!

!

!

!

!

Courtney!Baukal!and!Duncan!Clark!

11!November!2014!

Experiment!#11!

The!Synthesis!and!Analysis!of!Aspirin!

Chem!1315!–!085!

!

! !

Baukal,!Clark! 1!


! The!purpose!of!this!lab!is!to!conduct!a!spectrometric!analysis!of!your!aspirin.!!

It!exemplifies!the!BeerKLambert!Law!as!well.!

Lab!Quest!and!the!vernier!spectrometer!and!Melt!Temp!Apparatus!recorded!

the!values!being!analyzed!for!the!aspirin.!

! The!melting!point!of!aspirin!is!276.8!degrees!Fahrenheit!or!136!degrees!

Celsius.!!The!melting!point!of!pure!salicylic!acid!is!318.2!degrees!Fahrenheit!or!159!

degrees!Celsius.!!Beer!Lambert’s!law!is!A=ebc!where!A!=!log10P0/P!and!P!is!radiant!

power,!e!is!the!molar!absorptivity!in!L!molK1!cmK1,!b!is!the!length!of!the!cuvette!in!cm!

and!c!is!the!concentration!in!mol!LK1.!!A!calibration!curve!is!a!way!to!determine!the!

concentration!of!a!substance!by!comparing!it!to!a!known!sample.!


! Aspirin!crystals!were!analyzed.!!A!mortar!and!pestle!were!used!to!grind!up!

the!aspirin.!!The!melt!station!was!set!to!30!degrees!Celsius!higher!than!needed.!!The!

salicylic!acid!C6H4(OH)CO2H!was!recorded!to!the!nearest!0.002!grams.!!10!milliliters!

of!95%!ethanol!CH3CH2OH!was!used!along!with!0.025M!iron!(III)!nitrate!solution,!

Fe(NO3)3!and!distilled!water.!!A!cuvette!was!used!to!during!the!spectrometric!tests.!

Procedure:(

! Grind!up!a!small!amount!of!aspirin!and!pack!the!aspirin!into!a!capillary!tube!

to!about!½!inch!deep.!!Record!at!what!temperature!the!solid!turns!to!clear!liquid.!!

Repeat!with!a!synthesized!aspirin!sample.!!Measure!and!record!the!mass!of!0.20g!of!

salicylic!acid.!!Put!it!in!a!250mL!beaker!with!10!mL!of!ethanol;!then!add!150mL!of!

distilled!water.!!Transfer!solution!to!a!volumetric!flask!and!add!distilled!water!until!

Baukal,!Clark! 2!

there!are!250mL!in!the!flask.!!Calculate!the!molar!concentration.!!Add!10mL!of!

salicylic!acid!to!a!flask!and!add!0.025!M!Fe(NO3)3!until!the!flask!is!filled!to!100mL.!!

Prepare!three!more!salicylic!solutions!according!to!the!table!and!dilute!with!distilled!

water!and!calculate!the!molar!concentrations.!!Connect!and!calibrate!a!

spectrometer.!!Prepare!a!blank!by!filling!an!empty!cuvette!3/4ths!full!with!water!

and!calibrate.!!Use!the!first!solution!and!collect!data!for!two!minutes;!do!this!with!

the!remaining!solutions!as!well.!!Measure!out!0.5g!of!synthesized!aspirin!(record!

mass)!and!transfer!to!a!250mL!beaker.!!Add!10mL!of!ethanol!and!150mL!of!water!

then!transfer!to!flask!and!fill!up!to!250mL!with!water.!!Transfer!5mL!of!this!solution!

to!a!100mL!flask!and!add!0.025!M!Fe(NO3)3!to!fill!to!100mL.!!Record!the!absorbance!

of!the!aspirin!sample.!!Rinse!and!fill!the!cuvette!3/4th!full!with!the!sample!and!

record!absorbance.!!Repeat!this!a!few!more!times!with!new!aliquots!of!the!treated!

aspirin!sample.!


DATA TABLE

Part I- Melting Temperature Data

Pure Aspirin Synthesized Aspirin

Melting Temperature (°C) 138.7 123.4

Part II- Salicylic Acid Standard Stock Solution

Initial mass of salicylic acid (g) 0.214g

Moles of salicylic acid (mol) 0.002967

Initial molarity of salicylic acid (M) 0.011869

Baukal,!Clark! 3!

Part II- Beer’s Law Data for Salicylic Acid Standard Solutions

Trial Concentration (M) Absorbance 1 1.044758 1.919

2 0.783569 1.3340

3 0.522379 1.105

4 0.2611897 0.624

Part II- Test of the Purity of the Synthesized Aspirin

Initial mass of synthesized aspirin sample (g)

0.610

Absorbance of aspirin sample .670 1.072 2.005

Moles of salicylic acid in aspirin sample (mol)

0.03mol 0.05mol 0.11mol

Mass of salicylic acid in aspirin sample (g) 4.14354g 6.9059g 15.193g

Mass of aspirin in sample (g) 0.0122g 0.0244g 0.061g

Percent aspirin in sample (%) 0.000677% 0.001354% 0.003385%

Graph!1!

!

0!

0.5!

1!

1.5!

2!

2.5!

1.044758! 0.783569! 0.522379! 0.2611897!

Absorbance(

Concentration((M)(

Beer's(Law(

Baukal,!Clark! 4!

! The!theoretical!yield!of!aspirin!is!1.189!grams.!!The!percent!purity!of!the!

synthesized!aspirin!is!90.735%.!!The!percent!purity!does!not!compare!well!because!

there!should!theoretically!be!more!grams!of!aspirin!per!gram!of!salicylic!acid!and!

that!is!not!what!was!calculated!for!the!last!test.!!The!average!percent!yield!is!

0.269%.!!Most!sources!of!error!came!from!my!uncertainty!of!which!calculations!to!

do!using!which!numbers.!!Having!too!much!aspirin!in!our!initial!mass!may!have!also!

contributed!to!error.!

Calculations:(

! The!theoretical!yield!of!aspirin!is!calculated!by!

1!!!"#$%&!"#!!"#$ ∗ !!!!"#!!"#$%&#$%!"#.!"!#! ∗ !!!"#!!"#$%$&!!!"#!!"#$%&%#$% ∗ !

!"#.!"#!!!"#$%$&!!!"#!!"#$%$& =!1.1304g!of!aspirin.!!

The!purity!of!the!synthesized!aspirin!sample!is![123.4!(experimental!melting!point)/!

136!(theoretical!melting!point)]!*100=!90.735%.!!!For!Beer’s!law:![To!calculate!the!

molarity,!take!the!density!of!salicylic!to!get!the!moles!of!it.!!Then!use!moles/liters!to!

get!the!molarity!of!the!first!solution.!!Lastly!use!M1V1=M2V2!to!calculate!the!other!

concentrations.!!10mL!*!!.!!"!!!" ∗ !!"#

!"#.!!"!=!0.104476mol.!!!.!"##$%!"#!.!!"#$%& =1.044758M.!!For!

solution!2:!(!.!""#$%!∗!.!!"#!"#$%&)

!.!"!"#$%& =!0.783569M.!!For!solution!3:!

(!.!""#$%!∗!.!!"!"#$%&)!.!"!"#!"# =0.522379M.!!For!solution!4:!

(!.!""#$%!∗!.!!"#!"#$%&)!.!"!"#$%& =0.2611897M.]!!To!find!the!concentration!for!salicylic!acid,!look!

at!the!graph!and!determine!it!based!on!the!absorbance!values.!!To!find!the!moles,!

take!the!concentration!and!divide!it!by!0.1!since!there!is!only!100mL!instead!of!a!full!

liter.!!To!determine!moles,!multiply!the!concentration!by!the!molar!mass!

(138.118g/mol).!!To!calculate!the!percent!of!aspirin!in!the!sample:!convert!the!mass!

Baukal,!Clark! 5!

of!aspirin!into!moles!(0.61moles/180.154g/mol=!0.003386mol).!!Divide!the!moles!

by!liters!to!get!the!molarity!(0.003386mol/0.25liters=!0.0135mol/liter).!!Then!use!

M1V1=M2V2!to!calculate!the!molarity!(which!is!also!the!percent)!for!each!solution.!!

So!(0.0135*5)/100=0.000677mol/liter;!(0.0135*10)/100=0.001354mol/liter;!

(0.0135*25)/100=0.003385mol/liter.!!To!find!the!percent!yield!take!the!actual!

yield/theoretical!and!multiply!by!100;!the!theoretical!will!just!be!the!moles!of!

salicylic!acid!since!it!is!a!1!to!1!ratio.!!So!!.!"##!/!"#.!"#( !

!"#)!.!"!"# *100=0.226%;!

!.!"##!/!"#.!"#( !!"#)

!.!"!"# *100=0.27%;!!.!"#!/!"#.!"#( !

!"!)!.!!!"# *100=0.31%.!!To!find!the!average,!

add!up!all!three!percents!and!divide!by!three.!

References:(

"Beer's!Law!K!Theoretical!Principles."!Beer's&Law&*&Theoretical&Principles.!Web.!11!!

Nov.!2014.!

<http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/beers1.htm>.!

"Calibration!Curve."!Wikipedia.!Wikimedia!Foundation,!24!Oct.!2014.!Web.!11!Nov.!!

2014.!<http://en.wikipedia.org/wiki/Calibration_curve>.!

"Salicylic!Acid."!Wikipedia.!Wikimedia!Foundation,!14!Nov.!2014.!Web.!17!Nov.!!

2014.!<http://en.wikipedia.org/wiki/Salicylic_acid>.!

US!FDA!

!

r Lab 1-11

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Transcript of r Lab 1-11