Question

A vessel of volume $27 \times 10^{4}\text{ cc}$ contains a mixture of Hydrogen (molar mass $= 2\text{ g mol}^{-1}$) and Oxygen (molar mass $= 32\text{ g mol}^{-1}$) gas at standard temperature and pressure (S.T.P.). If the mass of hydrogen is $16\text{ g}$, find the mass of oxygen gas contained in the vessel.

• A. $64\text{ g}$
• B. $72\text{ g}$
• C. $129.7\text{ g}$
• D. $160\text{ g}$

Hint:

Always double-check that your volume is in liters or matching units before dividing by the S.T.P constant. Since $1\text{ L} = 1000\text{ cc}$, $27 \times 10^4\text{ cc} = 270\text{ L}$. Dividing $270$ by $22.4$ yields $\approx 12\text{ moles}$, which simplifies the calculation steps.

Answer 1

The Correct Option is C