A container holds 6.4 moles of gas. Hydrogen gas makes up [tex]$25 \%[tex]$[/tex] of the total moles in the container. The pressure is [tex]$[/tex]1.24 \, \text{atm}$[/tex]. What is the partial pressure of hydrogen?

Use [tex]\frac{P_a}{P_T}=\frac{n_a}{n_T}[/tex].

A. [tex]0.31 \, \text{atm}[/tex]
B. [tex]0.93 \, \text{atm}[/tex]
C. [tex]5.2 \, \text{atm}[/tex]
D. [tex]31 \, \text{atm}[/tex]



Answer :

To answer the question of finding the partial pressure of hydrogen in the container, follow these steps:

1. Identify the given values:
- Total moles of gas in the container, \( n_T = 6.4 \) moles.
- Fraction of hydrogen gas in the container, \( \text{Hydrogen fraction} = 0.25 \).
- Total pressure of the gas mixture, \( P_T = 1.24 \) atm.

2. Calculate the moles of hydrogen gas:
The fraction of hydrogen gas is \( 0.25 \) (or 25%), so the moles of hydrogen, \( n_H \), can be calculated as:
[tex]\[ n_H = \text{Hydrogen fraction} \times n_T = 0.25 \times 6.4 = 1.6 \text{ moles} \][/tex]

3. Use the formula for partial pressure:
The partial pressure of a gas in a mixture can be found using the relation:
[tex]\[ \frac{P_a}{P_T} = \frac{n_a}{n_T} \][/tex]
Where:
- \( P_a \) is the partial pressure of the gas (hydrogen in this case).
- \( P_T \) is the total pressure of the gas mixture.
- \( n_a \) is the moles of the gas (hydrogen in this case).
- \( n_T \) is the total moles of gas in the mixture.

4. Rearrange the formula to solve for \( P_a \):
[tex]\[ P_a = P_T \times \frac{n_a}{n_T} \][/tex]

5. Substitute the known values into the equation:
[tex]\[ P_H = 1.24 \times \frac{1.6}{6.4} \][/tex]

6. Simplify the fraction:
[tex]\[ \frac{1.6}{6.4} = 0.25 \][/tex]

7. Calculate the partial pressure:
[tex]\[ P_H = 1.24 \times 0.25 = 0.31 \text{ atm} \][/tex]

Therefore, the partial pressure of hydrogen in the container is \( 0.31 \) atm.

Among the given options:
- \( 0.31 \) atm
- \( 0.93 \) atm
- \( 5.2 \) atm
- \( 31 \) atm

The correct option is [tex]\( \boxed{0.31 \text{ atm}} \)[/tex].