Lab Assignment: Ideal Gas Law

Pre-Lab Questions

1. What is it in yeast that aids in the decomposition of hydrogen peroxide?

2. List the ideal gas law and define each term with units.

3. How many moles of O₂ were produced in a decomposition reaction of H₂O₂ if the barometric pressure was 0.980 atm, the temperature was 298 K and the volume of O₂ gas collected was 0.0500 L?

4. If you decomposed 10.00 mL of 100% H2O2, how many moles of O2 could you theoretically obtain?

Calculations

The goal is to find the percentage of hydrogen peroxide in the solution! This can be found by working through the following steps.

1. Convert the temperature of the water from ^oC to Kelvin (K). Use the equation K = ^oC + 273. This will be your value for absolute T or the temperature in Kelvin.

2. If necessary, convert the barometric pressure in the room from mm Hg to atmospheres (atm).

Divide the measured pressure from the Data section by 760 mm Hg. This will give you pressure (P) in atmospheres.

3. Convert the volume of oxygen from mL to liters (L).

4. Rearrange the ideal gas law to solve for n.

5. You are now ready to solve for the number of moles of O₂. Be sure the units cancel so that you end up with only the moles of O₂ left.

6. Calculate the theoretical number of moles of O₂ there would be if the hydrogen peroxide were 100%, and not an aqueous solution.

7. Find the percent hydrogen peroxide.

8. You can also easily determine the reaction rate. To do this, divide the total volume of oxygen collected by the total time of the reaction.

Post-Lab Questions

1. Was the calculated percentage of hydrogen peroxide close to the same as the percentage on the label?

2. Considering that catalysts are not consumed in a reaction, how do you think increasing the amount of catalyst would affect the reaction rate for the decomposition of hydrogen peroxide?