Part B. Temperature of the reaction:

Hydrochloric Acid-Sodium Thiosulfate

Reaction System.

Part C. Temperature of the reaction:

Oxalic Acid-Potassium Permanganate

Reaction System.

PART D. Presence of a Catalyst

PART E. Concentration of Reactants:

Magnesium-Hydrochloric acid System

PART F. Concentration of Reactants:

Iodic Acid-Sulfurous Acid System

1. Prepare the reactants.

1) Set up five, clean and labeled test tubes. Measure the volumesof the 0.01 M HIO3, starch, and water with 25-mL droppingpipets equipped with a silicone bulb of 1 mL capacity).

2) Calibrate the HIO3 dropping pipet to determine the volume(mL) per drop.[16] Calibrate a second dropping pipet withwater to determine the number of milliliters per drop.

3) Calibrate a third dropping pipet for the 0.01 M H2SO3 solutionthat delivers 1 mL; mark the level on the pipet so that quickdelivery of 1 ml of the H2SO3 solution to each test tube canbe made.

Solution in Test tubesAdd to test

tube

Test tube 0.01 M HIO3 Starch H2O 0.01 M H2SO3

1 6 drops 1 drop 14 drops 1.0 mL

2 10 drops 1 drop 10 drops 1.0 mL

3 14 drops 1 drop 6 drops 1.0 mL

4 20 drops 1 drop 0 drops 1.0 mL

Use 25-mL dropping pipets equipped with a silicone bulb of 1-ml capacity

2. Record the time for the reaction

1) Place a sheet of white paper beside the test tube. As onestudent quickly transfers 1.0 mL of the 0.01 M H2SO3 to therespective test tube, the other notes the time.

2) Immediately agitate the test tube; record the time lapse(seconds) for the deep-blue I3

-•starch complex to appear. * Beready! The appearance f the deep-blue solution is sudden.

HIO3 + H2SO3Test tube

1Test tube

2Test tube

3Test tube

4s (second) X 20.78 s 12.18 s 8.91 s

Summary

3. Complete remaining reactions

1) Repeat PART F.2. for the remaining reaction mixtures in Table23.1. Repeat any of the trials as necessary.[18]

4. Plot the data.

1) One one-half of a sheet of linear graph paper or by usingappropriate software, plot for each solution the initialconcentration of iodic acid, [HIO3]0 (y-axis), versus the time inseconds (x-axis) for the reaction.[19] * Remember that incalculating [HIO3]0, the total volume of the solution is the sum of thevolumes of the two solutions expressed in liters.

Cleanup

Rinse the test tubes twice with tap water anddiscard each into the Waste Inorganic Test Solutionscontainer. Two final rinses with distilled water can bediscarded in the sink.

Disposal: Dispose of all test solutions in the WasteInorganic Test Solutions container.

REPORT SHEET

Laboratory Manual For Principles Of General Chemistry, 10th edition

p.279 -280

EVALUATION CRITERIA▪ Pre-lab assignment (40 points)

- Summary: Theory (10 pts) andProcedure (10 pts)

- Pre-laboratory question (20 pts)▪ Lab Report (40 pts)▪ Post-lab assignment: Laboratory Questions

(20 pts)

1. Prepare the reactants.

1) Into a set of four clean, labeled test tubes, pipet 5 mL of 6 MHCl, 4 M HCl, 3 M HCl, and 1 M HCl, respectively (Figure 23.6).

2) Determine the mass (± 0.001 g)----separately (for eachsolution)----of four 1-cm strips of polished (with steel woolor sand paper) magnesium. Calculate the number of moles ofmagnesium in each strip.[13]

2. Record the time for completion of the reaction.

1) Add the first magnesium strip to the 6 M HCl solution. STARTTIME: record for all traces of the magnesium strip todisappear.

2) Repeat the experiment with the remaining three magnesiumstrips and the 4 M HCl, 3 M HCl, and 1 M HCl, solutions.[14]

3. Plot the data.

1) Plot (mol HCl ÷ mol Mg) (y-axis) versus time in seconds (x-axis) for the four tests on one-half of a sheet of linear graphpaper or by using appropriate software.

2) Have the TA approve your graph.[15]

Reaction of Mg with 6 M HCl 4 M HCl 3 M HCl 1 M HCls (second) 13.53 s 22.75 s 26.05 s 150.56 s

Summary

Hydrogen peroxide is relatively stable, but it readily decomposes in thepresence of a catalyst.

1. Add a catalyst.

1) Place approximately 2 mL of a 3% H2O2 solution in a clean,small test tube.

2) Add 1 or 2 crystals of MnO2 to the solution and observe. Noteits instability.[12]

The reaction rate for the oxidation-reduction reaction that occursbetween oxalic acid, H2C2O4 and potassium permanganate, KMnO4, ismeasured by recording the time elapsed for the (purple) color of thepermanganate ion, MnO4

-, to disappear in the reaction:

5 H2C2O4(aq) + 2 KMnO4(aq) + 2 H2SO4(aq) → 10 CO2(g) + 2MnSO4(aq) + K2SO4(aq) + 8 H2O(l) (23.2)

Measure the volume of each solution with separate clean graduatedpipets. As one student pours the test solutions together, the othernotes the time.

1. Prepare the solutions.

1) Into a set of three, clean 150-mm test tubes, pipet 1 mL of0.01 M KMnO4 (in 3 M H2SO4) and 4 mL of 3 M H2SO4.(Caution: KMnO4 is a strong oxidant and causes brown skinstrains; H2SO4 is a sever skin irritant and is corrosive. Donot allow either chemical to make skin contact.)

2) Into a second test set of three clean 150-mm test tubespipet 5 mL of 0.33 M H2C2O4.

2. Record the time for reaction at room temperature

1) Select a KMnO4-H2C2O4 pair of test tubes. Pour the H2C2O4

solution into the KMnO4 solution.

2) START TIME: Agitate the mixture. Record the time for thepurple color of the permanganate ion to disappear.

3) Record room temperature using all certain digits plus oneuncertain digit.[8]

3. Record the time for reaction at the higher temperature

1) Place a second KMnO4-H2C2O4 pair of test tubes in a warmwater (̴40oC) bath until thermal equilibrium is established(̴5 minutes).

2) Pour the H2C2O4 solution into the KMnO4 solution. STARTTIME: Agitate the mixture for several seconds, and returnthe reaction mixture to warm water bath.

3) Record the time for the disappearance of the purple color.

4) Record the temperature of the bath.[9]

4. Record the time for reaction at the highest temperature

1) Repeat Part C.3 but increase the temperature of the bathto ̴60oC.

2) Record the appropriate data.[10]

3) Repeat any of the preceding reactions as necessary.

5. Plot the data

1) Plot temperature (y-axis) versus time (x-axis) on one-halfof a sheet of linear graph paper or by using appropriatesoftware for the three data points.

2) Have the TA approve your graph.[7]

KMnO4-H2C2O4 20 °C 40 °C 56 °Cs (second) 112.50 s 33.00 s 5.56 s

Summary

Ask your TA to determine if both Part B and C are to be completed.You should perform the experiment with a partner; as one studentcombines the test solutions, the other notes the time.

The oxdidation-reduction reaction that occurs between hydrochloricacid and sodium thiosulfate, Na2S2O3, produces insoluble sulfur as aproduct.

2 HCl(aq) + Na2S2O3(aq) → S(s) + SO2(g) + 2 NaCl(aq) + H2O(l)(23.1)

The time required for the cloudiness of sulfur to appear is a measureof he reaction rate. Measure each volume of reactant with separategraduated pipets.

1. Prepare the solutions.

1) Pipet 2 mL of 0.1 M Na2S2O3 into each of a set of three150-mm, clean test tubes.

2) Into a second set of three 150-mm test tubes, pipet 2 mLof 0.1 M HCl. Label each set of test tubes.

3) Label each set of test tubes.

2. Record the time for reaction at the lower temperature

1) Place a Na2S2O3-HCl pair of test tubes in an ice water untilthermal equilibrium is established (̴5 minutes).

2) Pour the HCl solution into the Na2S2O3 solution, STARTTIME: Agitate the mixture for several seconds, and returnthe reaction mixture to the ice bath.

3) STOP TIME when the cloudiness of the sulfur appears.4) Record the time lapse for the reaction and the temperature

of the bath, using all certain digits plus one uncertaindigit.[4]

3. Record the time for reaction at the higher temperature

1) Place a Na2S2O3-HCl pair of test tubes in a warm water(<60oC) bath until thermal equilibrium is established (~5minutes).

2) Pour the HCl solution into the Na2S2O3 solution, STARTTIME: Agitate the mixture for several seconds, and returnthe reaction mixture to warm water bath.

3) STOP TIME when the cloudiness of the sulfur appears.4) Record the temperature of the bath.[5]

4. Record the time for reaction at room temperature

1) Combine the remaining set of Na2S2O3-HCl test solutions atroom temperature and proceed as in Parts B.2 and B.3.

2) Record the appropriate data.[6]

3) Repeat any of the above reactions as deemed necessary.

5. Plot the data

1) Plot temperature (y-axis) versus time (x-axis) on one-halfof a sheet of linear graph paper or by using appropriatesoftware for the three data points.

2) Have the TA approve your graph.[7]

3) Further interpret your data as suggested on the ReportSheet.

0.1 M Na2S2O3-0.1 M HCl 2 °C 20 °C 56 °Cs (second) 124.13 s 50.28 s 7.47 s

Summary

▪ Objectives

▪ Introduction

▪ Experimental Procedure & Result Videos

▪ Report Sheet

▪ Evaluation Criteria

OBJECTIVES

• To study the various factors that affect the rates of chemical reactions

INTRODUCTIONThe rate of chemical reaction is affected by several factors.

In this experiment, we will change chemicals, temperature and concentration.

Also, we will observe how the catalyst work.

EXPERIMENTAL

PROCEDURE &

RESULT VIDEOS

Overview

A series of qualitative experiments are conducted to

determine how various factors affect the rate of a chemicalreaction.Caution: A number of strong acids are used in the experiment.Handle with care; do not allow them to touch the skin orclothing.

Perform the experiment with a partner. At each circlessuperscript [1-19] in the procedure, stop and record yourobservation on the Report Sheet. Discuss your observationwith your lab partner and your TA.

Part A. Nature of the Reactants

1. Different acids affect reaction rates

1) Half-fill a set four labeled small test tubes (Figure 23.3)with 3 M H2SO4, 6 M HCl, 6 M CH3COOH, and 6 M H3PO4,respectively. (Caution: Avoid skin contact with the acids)

2) Submerge a 1-cm strip of magnesium ribbon into each testtube. Compare the reaction rates and record yourobservations.[1]

2. Different metals affect reaction rates

1) Half-fill a set of three labeled small test tubes (Figure 23.4)with 6 M HCl.

2) Submerge 1-cm strips of zinc, magnesium, and copperseparately into the test tubes.

3) Compare the reaction rates of each metal in HCl andrecord your observations.[2] Match the relative reactivityof the metals with the photos in Figure 23.5.[3]

Summary

Reaction of Mg with 3 M H2SO4 6 M HCl 6 M CH3COOH 6 M H3PO4

s (second) 37.94 s 16.94 s 57.59 s 130.78 s

Reaction of 6 M HCl with Zn Mg Cus (second) 16.94 s 144.03 s No Reaction

A1

A2