### Richard A. Paselk

General Chemistry

Spring 2008

Exercise: Chemical Equilibrium

# Chemical Equilibrium Problems

1. Consider the reaction

N2(g) + 3H2(g) 2NH3(g) + 92.2 kJ

Note that heat appears on the product side - the system is giving up heat, therefore H is negative, H = - 92.2 kJ

Using Le Châtelier's Principle, predict what will happen to [NH3] if:

• H2 is removed?
• T is decreased?

Predict how the equilibrium will shift (right, left, or neither) if:

• V is increased?

2. Consider the gas phase reaction:

2 HI H2 + I 2

Keq = 2.06 x 10-2 @ 458°C

If both hydrogen and iodine are measured to have concentrations of 0.0135 M each at 458°C, what is the concentration hydrogen iodide?

3. Consider the gas phase reaction:

2 HBr H2 + Br2

Keq = 1.5 x 10-5 @ 1400 K

Calculate the concentrations of all species at equilibrium if we start with 0.15 moles each of hydrogen bromide and bromine in a 0.500 L container at 1400 K.

4. Consider the gas phase dissociation of carbon dioxide to carbon monoxide and oxygen @ 1000 K.

If 0.200 moles of carbon dioxide is placed in a 1.00 L container at 1000 K calculate the concentrations of all species at equilibrium. Keq = 4.5 x 10-23 @ 1000 K.