College

\begin{tabular}{|l|l|}
\hline
Ideal gas law & [tex]$P V=n R T$[/tex] \\
\hline
Ideal gas constant & [tex]$R=8.314 \frac{L \cdot kPa}{mol \cdot K}$[/tex] \\
& or \\
& [tex]$R=0.0821 \frac{L \cdot atm}{mol \cdot K}$[/tex] \\
\hline
Standard atmospheric pressure & [tex]$1 \, atm=101.3 \, kPa$[/tex] \\
\hline
Temperature conversion & [tex]$K = {}^{\circ} C + 273.15$[/tex] \\
\hline
\end{tabular}

When a chemist collects hydrogen gas over water, she ends up with a mixture of hydrogen and water vapor in her collecting bottle. If the pressure is 97.1 kilopascals and the vapor pressure of the water is 3.2 kilopascals, what is the partial pressure of the hydrogen?

A. 93.9 kPa

B. 98.1 kPa

C. 100.3 kPa

D. 104.1 kPa

Answer :

Sure, let's break this down step-by-step.

We begin with the given values:
- The total pressure of the gas mixture (hydrogen gas and water vapor) is [tex]\( 97.1 \)[/tex] kilopascals (kPa).
- The vapor pressure of water is [tex]\( 3.2 \)[/tex] kilopascals (kPa).

We need to determine the partial pressure of the hydrogen gas.

According to Dalton's Law of Partial Pressures:
[tex]\[ \text{Total pressure} = \text{Partial pressure of hydrogen} + \text{Partial pressure of water vapor} \][/tex]

Let's denote:
- [tex]\( P_{\text{total}} \)[/tex] as the total pressure,
- [tex]\( P_{\text{H}_2} \)[/tex] as the partial pressure of hydrogen,
- [tex]\( P_{\text{H}_2O} \)[/tex] as the partial pressure of water vapor.

Given:
[tex]\[ P_{\text{total}} = 97.1 \, \text{kPa} \][/tex]
[tex]\[ P_{\text{H}_2O} = 3.2 \, \text{kPa} \][/tex]

We need to solve for [tex]\( P_{\text{H}_2} \)[/tex]. To do this, we rearrange Dalton's Law to find the partial pressure of hydrogen:
[tex]\[ P_{\text{H}_2} = P_{\text{total}} - P_{\text{H}_2O} \][/tex]

Substitute the known values:
[tex]\[ P_{\text{H}_2} = 97.1 \, \text{kPa} - 3.2 \, \text{kPa} \][/tex]

Perform the subtraction:
[tex]\[ P_{\text{H}_2} = 93.9 \, \text{kPa} \][/tex]

Hence, the partial pressure of the hydrogen gas is [tex]\( 93.9 \, \text{kPa} \)[/tex]. None of the provided options (9 kPa, 98.1 kPa, 100.3 kPa, 1OA F kPn) match the correct answer.