Chapter 5.4, Problem 5.10AFP

Interpretation Introduction

Interpretation:

In the mixture of noble gases, consisting of $5.50\text{g}$ of $\text{He}$, $15.0\text{g}$ of $\text{Ne}$, $35.0\text{g}$ of $\text{Kr}$ in a piston-cylinder assembly at STP, the partial pressure of each gas is to be calculated.

Concept introduction:

The formula to calculate number of moles is as follows:

$\text{Number}\text{of}\text{moles}\left(n\right)=\frac{\text{weight}\left(m\right)}{\text{Molecular}\text{weight}\left(M\right)}$        (1)

The formula to calculate the mole fraction is as follows:

$X_{\text{A}}=\frac{\text{Number}\text{of}\text{moles of component A}}{\text{Total}\text{number}\text{of}\text{moles in mixture}}$

The relation between partial pressure and mole fraction is as follows:

$\left(P_{\text{A}}\right)=\left(P_{\text{total}}\right)\left(X_{\text{A}}\right)$        (2)

Here,

$P_{\text{A}}$ is the partial pressure of gas A.

$X_{\text{A}}$ is mole fraction of gas A.

$P_{\text{total}}$ is the total pressure.

Equation (2) can be modified as follows:

$P_{\text{A}}=\left(\frac{\text{Number}\text{of}\text{moles of component A}}{\text{Total}\text{number}\text{of}\text{moles in mixture}}\right)\left(P_{\text{total}}\right)$        (3)