# Problem: Hydrogen peroxide (H2O2) decomposes in the presence of a catalyst to form water and oxygen. The catalyst is added to 5.00 mL of a hydrogen peroxide solution at 25.0˚C, and 49.5 mL of gas is collected over water at a total pressure of 763.6 mmHg.How many moles of oxygen are collected?

###### FREE Expert Solution

Solve for PO→ moles O2

Using Dalton’s Law: PO2
at 25.0°C, Pwater = 23.78 mm Hg (vapor pressure)

${\mathbit{P}}_{{\mathbf{O}}_{\mathbf{2}}}\mathbf{=}$739.82 mmHg

Ideal Gas equation: moles O2

$\mathbf{PV}\mathbf{=}\mathbf{nRT}\phantom{\rule{0ex}{0ex}}\overline{){\mathbf{n}}{\mathbf{=}}\frac{\mathbf{PV}}{\mathbf{RT}}}$

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###### Problem Details

Hydrogen peroxide (H2O2) decomposes in the presence of a catalyst to form water and oxygen. The catalyst is added to 5.00 mL of a hydrogen peroxide solution at 25.0˚C, and 49.5 mL of gas is collected over water at a total pressure of 763.6 mmHg.

How many moles of oxygen are collected?