Gas Laws Fact Sheet

\begin{tabular}{|l|l|}
\hline
Ideal gas law & [tex]$PV = nRT$[/tex] \\
\hline
\multirow{2}{*}{Ideal gas constant} & [tex]$R = 8.314 \frac{L \cdot kPa}{mol \cdot K}$[/tex] \\
& [tex]$R = 0.0821 \frac{L \cdot atm}{mol \cdot K}$[/tex] \\
\hline
Standard atmospheric pressure & [tex]$1 \, atm = 101.3 \, kPa$[/tex] \\
\hline
\end{tabular}

A scuba diver's air tank contains oxygen, helium, and nitrogen at a total pressure of 205 atmospheres. The partial pressure of nitrogen is 143 atmospheres, and the partial pressure of helium is 41 atmospheres. What is the partial pressure of oxygen in the tank?

A. 21 atm
B. 103 atm
C. 307 atm
D. 389 atm



Answer :

To solve this problem, we'll need to make use of the concept of partial pressures in a gas mixture. The total pressure of a mixture of gases is the sum of the partial pressures of each individual gas. This concept is described by Dalton's Law of Partial Pressures.

Given in the problem:
- Total pressure in the tank: [tex]\( P_{total} = 205 \)[/tex] atmospheres
- Partial pressure of nitrogen: [tex]\( P_{N_2} = 143 \)[/tex] atmospheres
- Partial pressure of helium: [tex]\( P_{He} = 41 \)[/tex] atmospheres

We are asked to find the partial pressure of oxygen [tex]\( P_{O_2} \)[/tex].

According to Dalton's Law of Partial Pressures:
[tex]\[ P_{total} = P_{N_2} + P_{He} + P_{O_2} \][/tex]

Rearranging the equation to solve for [tex]\( P_{O_2} \)[/tex]:
[tex]\[ P_{O_2} = P_{total} - (P_{N_2} + P_{He}) \][/tex]

Substitute the given values:
[tex]\[ P_{O_2} = 205 \, \text{atm} - (143 \, \text{atm} + 41 \, \text{atm}) \][/tex]
[tex]\[ P_{O_2} = 205 \, \text{atm} - 184 \, \text{atm} \][/tex]
[tex]\[ P_{O_2} = 21 \, \text{atm} \][/tex]

Therefore, the partial pressure of oxygen in the tank is [tex]\( 21 \)[/tex] atmospheres. The correct answer is:
A. 21 atm