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A student used 4.972 grams of hydrogen peroxide and roughly 10mL of 1.0 M KI and

ID: 826196 • Letter: A

Question

A student used 4.972 grams of hydrogen peroxide and roughly 10mL of 1.0 M KI and produced a 71.1 mL volume of gas. The experiment was performed at 27 degrees C. The atmospheric pressure was 761.4 torr.


a) What was the partial pressure (in torr) of water vapor in the 100ml cylinder?


b) What was the partial pressure (in torr) of O2 in the 100ml cylinder?


c) What was the partial pressure (in atm) of O2 in the 100ml cylinder?


d) How many moles of O2 were produced?


e) How many moles of H2O2 were consumed?


f) What mass of H2O2 was consumed?


g) What was the percent by mass of H2O2 in the original solution?

Explanation / Answer

The hydrogen peroxide will decompose to give water and oxygen, potassium Iodide is acting as a catalyst

2H2O2(l)-------------> 2H2O(g) + O2(g)


Moles of HI initially = 4.972/128 = 0.039

moles of KI = 0.01 x 1.0 = 0.01 moles


As one mole of HI reacts with one mole of KI,

e) 0.01 moles of HI were consumed.