Practice Le Chatelier's Principle in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

When a system at chemical equilibrium is subjected to an external stress โ€” such as a change in concentration, pressure, or temperature โ€” the equilibrium.

Push on equilibrium, and it pushes back. Add something, and the system uses it up.

Showing a random 20 of 50 problems.

Example 1

medium
For AgCl(s)โ‡ŒAg+(aq)+Clโˆ’(aq)\text{AgCl}(s)\rightleftharpoons \text{Ag}^+(aq)+\text{Cl}^-(aq), adding NaCl(aq)\text{NaCl}(aq) has what effect on the solubility of AgCl?

Example 2

easy
For an exothermic reaction at equilibrium, does cooling shift it toward reactants or products?

Example 3

medium
Why does changing concentration shift the equilibrium position but NOT change KK, while changing temperature changes KK?

Example 4

medium
For CO2(g)+H2O(l)โ‡ŒH2CO3(aq)\text{CO}_2(g)+\text{H}_2\text{O}(l)\rightleftharpoons \text{H}_2\text{CO}_3(aq), opening a carbonated drink bottle causes what shift?

Example 5

medium
For 2SO2(g)+O2(g)โ‡Œ2SO3(g)2\text{SO}_2(g)+\text{O}_2(g)\rightleftharpoons 2\text{SO}_3(g), ฮ”H<0\Delta H<0. Predict the shift for: (a) adding O2\text{O}_2, (b) raising T, (c) raising P, (d) removing SO3\text{SO}_3.

Example 6

medium
For A(g)โ‡Œ2B(g)\text{A(g)}\rightleftharpoons2\text{B(g)}, the number of gas moles increases left to right. Does decreasing pressure favor reactant or product?

Example 7

easy
Le Chatelier's principle: if you add more reactant to a system at equilibrium, which way does it shift?

Example 8

medium
For N2O4(g)โ‡Œ2NO2(g)\text{N}_2\text{O}_4(g)\rightleftharpoons 2\text{NO}_2(g), ฮ”H>0\Delta H>0. When the temperature is raised, what happens to (a) KcK_c and (b) the equilibrium [NO2][\text{NO}_2]?

Example 9

easy
If you remove a product from a system at equilibrium, which way does it shift?

Example 10

medium
At constant volume, an inert gas (e.g., Ar) is added to N2(g)+3H2(g)โ‡Œ2NH3(g)\text{N}_2(g)+3\text{H}_2(g)\rightleftharpoons 2\text{NH}_3(g). Predict the shift.

Example 11

medium
For the equilibrium CaCO3(s)โ‡ŒCaO(s)+CO2(g)\text{CaCO}_3\text{(s)} \rightleftharpoons \text{CaO(s)} + \text{CO}_2\text{(g)} (endothermic), predict the effect of increasing temperature on the amount of CO2\text{CO}_2 produced.

Example 12

medium
For CaCO3(s)โ‡ŒCaO(s)+CO2(g)\text{CaCO}_3(s)\rightleftharpoons \text{CaO}(s)+\text{CO}_2(g), predict the effect of (a) removing CO2\text{CO}_2, (b) adding more CaCO3\text{CaCO}_3.

Example 13

easy
Adding an inert gas at constant volume changes the total pressure. Does it shift the equilibrium position?

Example 14

medium
In the Haber process N2+3H2โ‡Œ2NH3\text{N}_2+3\text{H}_2\rightleftharpoons2\text{NH}_3 (exothermic), why is a compromise moderate temperature used instead of low temperature?

Example 15

medium
For 2NO(g)+O2(g)โ‡Œ2NO2(g)2\text{NO}(g)+\text{O}_2(g)\rightleftharpoons 2\text{NO}_2(g), ฮ”H<0\Delta H<0. Predict the effect on yield of: (a) raising T, (b) increasing P, (c) removing NO2\text{NO}_2.

Example 16

easy
For N2+3H2โ‡Œ2NH3\text{N}_2+3\text{H}_2\rightleftharpoons2\text{NH}_3, increasing pressure favors which side?

Example 17

medium
For the exothermic reaction N2+3H2โ‡Œ2NH3+heat\text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3 + \text{heat}, predict the effect of: (a) increasing temperature, (b) removing NH3\text{NH}_3, (c) increasing pressure.

Example 18

challenge
For exothermic N2+3H2โ‡Œ2NH3\text{N}_2+3\text{H}_2\rightleftharpoons2\text{NH}_3, you simultaneously raise temperature and pressure. Predict the competing effects on NH3\text{NH}_3 yield.

Example 19

medium
In 2NO2โ‡ŒN2O42\text{NO}_2\rightleftharpoons\text{N}_2\text{O}_4, the system is compressed (volume halved). Predict the shift and explain.

Example 20

easy
Does adding a catalyst shift the equilibrium position?
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