# A chemical reaction produced a 0.311 g sample of gas which occupied 225 mL at 55 C exerting a...

## Question:

A chemical reaction produced a {eq}0.311\ g {/eq} sample of gas which occupied {eq}225\ mL {/eq} at {eq}55 ^\circ C {/eq} exerting a pressure of {eq}886\ mm -Hg {/eq}. What is the molar mass of the gas?

## Molar Mass:

Molar mass is a very useful quantity in Chemistry. It is the ratio of the total mass of a substance per mole. This quantity can be used in order to determine the number of moles of a substance given its measured mass.

Determine the molar mass of the given gas by dividing the acquired mass by the number of moles of gas there is using the ideal gas equation, {eq}\displaystyle n = \frac{PV}{RT} {/eq}, where {eq}\displaystyle P {/eq} is the pressure, {eq}\displaystyle V {/eq} is the volume, {eq}\displaystyle R {/eq} is the gas constant, {eq}\displaystyle T {/eq} is the temperature. We proceed with the soltuion.

{eq}\begin{align} \displaystyle \frac{m}{n} &= \frac{m}{ \frac{PV}{RT}}\\ &= \frac{3.11\ g}{\frac{886\ mmHg\cdot 0.225\ L}{62.363\ \rm{L\ mmHg/mol\ K}\cdot (55+273\ K)}}\\ &\approx 319\ \rm{g/mol} \end{align} {/eq} 