Answer :
Given information,
A 6.0-L flask contains a mixture of methane (CH4), argon, and helium at 45degreeC and 1.75 atm.
The mole fractions of helium and argon are 0.25 and 0.35 respectively.
Calculate the number of methane molecules are present,
[tex]$\mathrm{V}=6.0 \mathrm{~L}=0.006 \mathrm{~m}^{3} ; \mathrm{T}=45^{0} \mathrm{C}=318.15 \mathrm{~K} ; \mathrm{P}=1.75 \mathrm{~atm}=177318.75 \mathrm{~Pa}$[/tex]
Mole fraction of methane [tex]$=1-0.25-0.35=0.4$[/tex]
[tex]\begin{aligned}\mathrm{P}_{\text {methane }} &=\mathrm{P} \times \text { mole fraction }=177318.75 \mathrm{~Pa} \times 0.4=70927.5 \mathrm{~Pa} \\\mathrm{PV} &=\mathrm{nRT}=(\mathrm{NRT}) / \mathrm{N}_{\mathrm{A}} \\\mathrm{N} &=\left(\mathrm{pVN}_{\mathrm{A}}\right) /(\mathrm{RT}) \\\mathrm{N} &=\frac{70927.5 \times 0.006 \times 6.022 \times 10^{23}}{8.314 \times 318.15} \\&=9.69 \times 10^{22} \text { molecules }\end{aligned}$[/tex]
The mole fraction is one of several methods for expressing the solution's concentration. A unit of concentration is a mole fraction. The mole fraction, which is denoted by "X," is a unit of measurement for the ratio of solute to solvent in a solution.
The mole fraction is not temperature-dependent.
Calculating the mole fraction does not need knowledge of the phase's density.
The mole fraction of an ideal gas mixture is expressed by the mixture's partial pressure to total pressure ratio.
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