# A 0.2 mol sample of N2 , CO2 with a pressure of 840 torr is exposed to solid CaO which react with theCO2 to form solidCaCO3 assume the reaction goes to completion complete pressure the gas had dropped to 320 how many moles of CO2 in origin mixtur? how

Mar 3, 2018

$\text{0.124 moles}$.

#### Explanation:

The total pressure in a gas is the sum of the partial pressures of the components, that, at the same temperature and constant volume, are proportional to the molar fractions of the components themselves.

The mixture of ${\text{CO}}_{2}$ and ${\text{N}}_{2}$ gases, after absorption of ${\text{CO}}_{2}$ by $\text{CaO}$, drops by $\text{520 torr}$, which corresponds to the proportion of ${\text{CO}}_{2}$ over the total gas.

$\frac{520}{820} = \frac{x}{0.2}$

So

$x = \text{0.124 moles}$

of ${\text{CO}}_{2}$ were present in the original mixture.