Question

Sumazrize The Experiment? Into steps

Introduction

The decomposition of hydrogen peroxide in aqueous solution proceeds very slowly. A bottle of 3% hydrogen peroxide sitting on a grocery store shelf is stable for a long period of time. The decomposition takes place according to the reaction below. 2 H2O2(aq) → 2 H2O + O2(g) A number of catalysts can be used to speed up this reaction, including potassium iodide, manganese (IV) oxide, and catalase (an enzyme). If you conduct the catalyzed decomposition of hydrogen peroxide in a closed vessel, you will be able to determine the reaction rate as a function of the pressure increase in the vessel that is caused by the production of oxygen gas. If you vary the initial molar concentration of the H2O2 solution, the rate law for the reaction can also be determined. Finally, by conducting the reaction at different temperatures, the activation energy, Ea, can be calculated.

Procedure

1. Obtain and wear goggles. 2. Connect a Gas Pressure Sensor to a computer interface or handheld. Connect the interface to the computer using the proper cable. 3. Place containers with ~15 mL of 3% H2O2, ~10 mL of 0.5 M KI, and ~50 mL of distilled water in a cold water bath that will chill the three liquids to a temperature that will be very close to 10 °C cooler than room temperature. You will use these cold liquids in your 4th trial run of the reaction. 4. Start the data-collection application. Set up the time-based mode to collect pressure readings every several seconds for five minutes. 5. Set up the experiment apparatus: a. Measure out 45 mL of distilled water into a 125 mL Erlenmeyer flask. b. Measure out 10 mL of 3% H2O2 into the flask. Note: Assuming a 3.0% concentration and a density of 1.00 g/mL, the concentration of H2O2 is 0.88 M. CHEM1112 General Chemistry II Laboratory Spring 20163 Decomposition of Hydrogen Peroxide. c. Use a temperature probe or thermometer to measure the temperature of the mixture in the flask, and record this value in your data table. d. Carefully place a magnetic stirring bar into the flask. e. Place a magnetic stirrer on the base of a ring stand. Use a utility clamp to fasten the flask to the ring stand as shown in Figure 1. f. Position the flask at the center of the magnetic stirrer. Test the stirrer speed. Select a moderately slow stirring speed that you will use throughout this experiment, and note the position of the control knob. g. Use the plastic tubing with two Luer-lock connectors to connect the two-hole rubber stopper assembly to the Gas Pressure Sensor, as shown in Figure 1. About one-half turn of the fittings will secure the tubing tightly. The valve connected to the stopper should stay closed during this experiment. h. Measure out 5 mL of 0.5 M KI solution into a 10-mL graduated cylinder. Assume that it is at the same temperature as the water and H2O2 mixture. 6. Prepare to start data collection. a. Transfer the 5 mL of KI solution into the flask. b. Tightly seal the flask with the two-hole stopper connected to the Gas Pressure Sensor. c. Ensure that the flask is properly positioned. Turn the stirrer on to the predetermined setting. 7. Start the data collection. Note: If the pressure exceeds 130 kPa, the pressure inside the flask will be too great and the rubber stopper is likely to pop off. Carefully remove the stopper from the flask if the pressure exceeds 130 kPa. 8. When the data collection is complete, carefully remove the stopper from the flask to relieve the pressure. Dispose of the contents of the flask as directed. 9. Examine the pressure vs. time graph. Find the steepest 20-second segment, and calculate the best-fit linear equation for this segment. Write down the slope of the line, m, as the initial rate of the reaction, in kPa/s. 10. Rinse and clean the flask for the next run. 11. Repeat the necessary steps for Runs 2–4. Use the volumes of H2O2, KI, and distilled water shown in the chart below. For Run 4, remember to use the liquids in the cold water bath. Measure and record the temperature of the water bath. Ideally, the CHEM1112 General Chemistry II Laboratory Spring 20164 Decomposition of Hydrogen Peroxide. temperature of the liquids in Run 4 should be very close to 10 °C cooler than the temperature of Runs 1–3.

Answer 1

Summary

1) Decomposition of hydrogen peroxide in aqueous solution proceeds very slowly,so the rate of decomposition of 3% H2O2 is measured in the presence of catalysts like potassium iodide, manganese (IV) oxide, and catalase (an enzyme).It decomposes as per the reaction 2 H2O2(aq) → 2 H2O + O2(g)

To yield oxygen. So in a closed vessel, the reaction rate is a function of the pressure increase in the closed vessel where it is carried out . Finally, by conducting the reaction at different temperatures, the activation energy, Ea, can be calculated using Arrhenius equation.

K=A exp(-Ea/RT)

K=rate constant,

R=universal gas constant

T= temperature

Procedure

1) To measure the oxygen gas pressure a Gas Pressure Sensor connected to a computer interface or handheld is used.

2) The reactants ~15 mL of 3% H2O2, ~10 mL of 0.5 M KI, and ~50 mL of distilled water are to be maintained at close to 10 °C.These are to be used in your 4th trial run of the reaction.

3) Start the data-collection application. Set up the time-based mode to collect pressure readings every several seconds for five minutes.

4). Set up the experiment apparatus:

Measure out 45 mL of distilled water ,10ml of 3% H2O2 (0.88M) into a 125 mL Erlenmeyer flask. b. Measure out 10 mL of 3% H2O2 into the flask.

5) Use a thermometer to measure the temperature of the mixture in the flask, and record this value in your data table. A magnetic stirring bar is used to stir the contents in the flask at moderate speed.

6 ) most importantly, a plastic tubing with two Luer-lock connectors is to be used to connect the two-hole rubber stopper assembly to the Gas Pressure Sensor. The valve connected to the stopper should stay closed during this experiment.

7) Measure out 5 mL of 0.5 M KI solution into a 10-mL graduated cylinder, start data collection and then transfer the 5 mL of KI solution into the flask to start the reaction

8) Tightly seal the flask with the two-hole stopper connected to the Gas Pressure Sensor and turn the stirrer on. Start the data collection.

9) Do not let the pressure exceeds 130 kPa, as the rubber stopper is likely to pop off.Carefully remove the stopper from the flask if the pressure exceeds 130 kPa.

10) plot and examine the pressure vs. time graph. calculate the best-fit linear equation for a small time segment.

Repeat the experiment for 2-4 runs. Slope, m, is the initial rate of the reaction, in kPa/s.