Question

A vessel contains a mixture of gases. The mass of each gas used to make the mixture is known. Which of the following information is needed to determine the mole fraction of each gas in the mixture? The molar mass of each gas A The density of the gases in the vessel B The total pressure of the gases in the vessel C The number of atoms per molecule for each gas

Answer 1

Answer: The molar mass of each gas

Explanation:

Mole fraction is the ratio of moles of that component to the total moles of solution. Moles of solute is the ratio of given mass to the molar mass.

$\text{Mole fraction of solute}=\frac{\text{Moles of solute}}{\text{Total Moles}}$

Suppose if there are three gases A, B and C.

a) $\text{Mole fraction of A}=\frac{\text{Moles of A}}{\text{ Moles of (A+B+C)}}$

b) $\text{Mole fraction of B}=\frac{\text{Moles of B}}{\text{ Moles of (A+B+C)}}$

c) $\text{Mole fraction of C}=\frac{\text{Moles of C}}{\text{ Moles of (A+B+C)}}$

moles of solute =$\frac{\text {given mass}}{\text {Molar mass}}$

Thus if mass of each gas is known , we must know the molar mass of each gas to know the moles of each gas.