III. Gas-Phase Equilibria
III-1. Introduction and Background III-2. Sample Problem III-3. List of Problems III-4. Simple Problems III-5. Advanced Problems

### Introduction

Gas-phase equilibria are important in a variety of environmental and industrial chemical situations. In general a gas or gases will exist in equilibrium with other gases or solids. In the atmosphere, nitrogen and sulfur oxides produced in combustion contribute to pollutants. In the Haber process, a major industrial process, manipulating the equilibrium conditions is the primary way to produce NH3 from N2 and H2. For information on how gas-phase reactions compare to other types of reactions, see the background document on chemical reactions.

### Problem-Solving Tips

In the simple problems, partial pressures are given to use in the equilibrium calculations. In more complicated problems you will often be given moles or grams of gas; or temperature, pressure or volume conditions might change shifting the equilibrium. In these cases use the ideal gas law.

The ideal gas law is:    PV = nRT

where:
P is partial pressure in atm
V is volume in L
n is number of moles of gas
R is the Gas Constant: 0.0820578 L atm mol-1 K-1
T is temperature in K.

CHP Home Equilibrium Practice Problems