A sample of H2 is collected over water such that the combined hydrogen–water vapor sample is held at a pressure of 1 standard atmosphere. What is the partial pressure of the H2 if that of the water vapor is 2.5 kPa?
A. 103.8 kPa
B. 98.8 kPa
C. 2.5 kPa
D. 101.3 kPa
B or C???
1 atm is about 1.013*10^5 Pa or 101.3 kPa
101.3 - 2.5 = 98.8
98.8
To calculate the partial pressure of H2, you need to subtract the pressure of water vapor from the total pressure.
Given:
Total pressure = 1 standard atmosphere = 101.3 kPa
Pressure of water vapor = 2.5 kPa
Partial pressure of H2 = Total pressure - Pressure of water vapor
Partial pressure of H2 = 101.3 kPa - 2.5 kPa
Partial pressure of H2 = 98.8 kPa
So, the correct option is B. 98.8 kPa.
To determine the partial pressure of H2 in the sample, you need to know that the total pressure of the combined hydrogen and water vapor sample is 1 standard atmosphere (which is equal to 101.3 kPa).
If the partial pressure of the water vapor is given as 2.5 kPa, you can subtract this value from the total pressure to find the partial pressure of H2.
So the partial pressure of H2 is 101.3 kPa - 2.5 kPa = 98.8 kPa.
Therefore, the correct answer is B. 98.8 kPa.