Worksheet: Concentration Changes in Equilibria

In this worksheet, we will practice calculating changes in the concentrations of reactants and products due to shifts in the position of equilibrium.


Consider the following equilibrium. 4NO()+6HO()4NH()+7O()2232gggg

Which of the following is the correct expression for the equilibrium constant (𝐾c) of the reaction?

  • A𝐾=[][][[]c3222NHONO]HO
  • B𝐾=[][][][]c22324NO6HO4NH7O
  • C𝐾=[][][]c3222NHONO[HO]
  • D𝐾=[][][][]c2232NOHONHO
  • E𝐾=[][][[]c32224NH7O4NO]6HO

How must the concentration of NH3 change to reach equilibrium if the reaction quotient is less than the equilibrium constant?

  • AIncrease
  • BDecrease
  • CStay the same

If the reaction were at equilibrium, how would a decrease in pressure (from an increase in the volume of the reaction vessel) change the pressure of NO2?

  • AStay the same
  • BDecrease
  • CIncrease

If the change in the pressure of NO2 is 28 torr as a mixture of the four gases reaches equilibrium, how much would the pressure of O2 have changed?


A suspension contains solid Mg(OH)2 in equilibrium with dissolved Mg2+ and OH ions. If solid KOH is added to the suspension, which of the following effects is not observed?

  • A[Mg]2+ decreases.
  • B[OH] decreases.
  • CThe pH increases.
  • D[K]+ increases.
  • EThe amount of solid Mg(OH)2 increases.

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