Humboldt State University ® Department of Chemistry

Richard A. Paselk

	General Chemistry	Spring 2008
Exercise: Chemical Equilibrium	© R. Paselk 2008
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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:

• N₂ is added?
• H₂ is removed?
• T is decreased?
• Ar is added?

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

K_eq = 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

K_eq = 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. K_eq = 4.5 x 10^-23 @ 1000 K.

Answers 1-4

In addition to these exercises you should familiarize yourself with text materials.

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© R A Paselk

Last modified 4 December 2008