Worksheet 4.3 - Partial
Pressure
Supplemental Instruction
Iowa State University
Gas Law Constants:
.08206 L*atm/mol*K
8.314 J/mol*K
1.987 cal/mol*K
8.314 (m^3)Pa/mol*K
62.36 L*torr/mol*K
Leader:Lea
Course:Chem 177
Instructor:Dr. Schewe-Miller
Date:4/21/2013
Equations:
PV=nRT
P1V1 = P2V2
V1/T1 = V2/T2
V1/N1 = V2/N2
n/V = P/RT
d = PM/RT
M = dRT/P
Terms:
-Dalton’s Law of Partial Pressures
-Effusion
-Diffusion
-Kinetic-Molecular Theory of Gases
1. You have a mixture of gases containing 2 mol H2, 1.5 mol O2, and 1 mol CO2 in a 2L vessel at
25 degrees C. What is the partial pressure of each of the gases? What is the total pressure in
the vessel?
2. You have a mixture of two gases, A and B, in a vessel with fixed volume and temperature.
Answer the questions for the following scenarios:
a. Some of gas A is removed. What will happen to the partial pressure of gas A? What will
happen to the overall pressure? What will happen to the partial pressure of gas B? What will
happen to the mole fraction of gas B?
b. A third gas, gas C, is added. What will happen to the partial pressures of gases A and B? What
will happen to the overall pressure? What will happen to the mole fraction of gas A?
3. You have a mixture in a fixed volume vessel containing 4 mol of O2, 3 mol H2, and .4 mol Xe.
Calculate the mole fraction for each, and the partial pressure for each assuming total pressure
is equal to 1.23 atm.
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4. You collect .5L of a gas over water at 24 degrees C and 1 atm of pressure. Calculate the partial
pressure of this gas. How many moles of gas did you collect?
5. What happens to average speed when the temperature of a gas is increased?