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 in the collecting bottle 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. 104.5 kPa

To find the partial pressure of the hydrogen gas collected, you need to use the concept of partial pressures, which states that the total pressure in a container is the sum of the partial pressures of all gases present.

Here’s how you can solve the problem step-by-step:

1. Understand the given values:
- The total pressure in the collecting bottle is 97.1 kilopascals (kPa).
- The vapor pressure of water in the bottle is 3.2 kilopascals (kPa).

2. Apply Dalton's Law of Partial Pressures:
- Dalton's Law states that the total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture.
- In this case, the total pressure is the sum of the partial pressure of hydrogen and the vapor pressure of water.

3. Calculate the partial pressure of hydrogen:
- To find the partial pressure of hydrogen, subtract the vapor pressure of water from the total pressure.
- [tex]\( \text{Partial Pressure of Hydrogen} = \text{Total Pressure} - \text{Vapor Pressure of Water} \)[/tex]
- [tex]\( \text{Partial Pressure of Hydrogen} = 97.1 \, \text{kPa} - 3.2 \, \text{kPa} = 93.9 \, \text{kPa} \)[/tex]

The partial pressure of the hydrogen gas is 93.9 kPa.

Therefore, the correct answer is:
A. 93.9 kPa