Practice Equilibrium Constant in Chemistry

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

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Quick Recap

The ratio of product concentrations to reactant concentrations at equilibrium, each raised to its stoichiometric coefficient.

K is the scoreboard at the end of the game β€” it tells you which side won. Large K means products dominate; small K means reactants dominate.

Showing a random 20 of 50 problems.

Example 1

medium
For a reaction with Ξ”ngas=0\Delta n_{gas} = 0, how are KpK_p and KcK_c related?

Example 2

easy
If K=1K = 1, what does that say about products and reactants at equilibrium?

Example 3

easy
Write the equilibrium expression KcK_c for Aβ‡ŒBA \rightleftharpoons B.

Example 4

medium
Reaction Aβ‡ŒBA \rightleftharpoons B has K=8K = 8 at 300300 K. After increasing TT, KK becomes 44. Is the forward reaction endothermic or exothermic?

Example 5

hard
Two reactions: R1R_1: Aβ‡ŒBA \rightleftharpoons B, K1=4K_1 = 4. R2R_2: 2Bβ‡ŒC2B \rightleftharpoons C, K2=9K_2 = 9. Find KK for 2Aβ‡ŒC2A \rightleftharpoons C.

Example 6

medium
At equilibrium [A]=2.0[A]=2.0 M, [B]=4.0[B]=4.0 M for Aβ‡ŒBA \rightleftharpoons B. Find KcK_c.

Example 7

challenge
For N2+3H2β‡Œ2NH3N_2 + 3H_2 \rightleftharpoons 2NH_3, equilibrium gives [N2]=1.0[N_2]=1.0, [H2]=2.0[H_2]=2.0, [NH3]=4.0[NH_3]=4.0 M. Compute KcK_c.

Example 8

medium
If Kforward=4K_{forward} = 4, what is KK for the reverse reaction?

Example 9

medium
For N2O4β‡Œ2NO2N_2O_4 \rightleftharpoons 2NO_2, [N2O4]=0.040[N_2O_4] = 0.040 M and [NO2]=0.040[NO_2] = 0.040 M at equilibrium. Find KcK_c.

Example 10

medium
For 2Aβ‡ŒB2A \rightleftharpoons B, Kc=25K_c = 25 and [A]=0.20[A] = 0.20 M at equilibrium. Find [B][B].

Example 11

medium
For Aβ‡ŒBA \rightleftharpoons B, K1=4K_1 = 4. If reaction 2 is Bβ‡ŒAB \rightleftharpoons A, what is K2K_2?

Example 12

medium
Write KcK_c for the heterogeneous equilibrium 2NaHCO3(s)β‡ŒNa2CO3(s)+H2O(g)+CO2(g)2NaHCO_3(s) \rightleftharpoons Na_2CO_3(s) + H_2O(g) + CO_2(g).

Example 13

easy
What is the symbol for the reaction quotient (not at equilibrium)?

Example 14

challenge
Phosgene decomposes: COCl2β‡ŒCO+Cl2COCl_2 \rightleftharpoons CO + Cl_2, Kc=0.090K_c = 0.090 at TT. A 1.01.0 L flask holds 1.01.0 mol COCl2COCl_2 initially. Find [CO][CO] at equilibrium.

Example 15

medium
A reaction Aβ‡Œ2BA \rightleftharpoons 2B has K=9K = 9. If [A]=1.0[A] = 1.0 M at equilibrium, find [B][B].

Example 16

medium
A reaction has Q=1Q = 1 and K=5K = 5. Which direction does it shift?

Example 17

hard
For N2O4β‡Œ2NO2N_2O_4 \rightleftharpoons 2NO_2 in the gas phase at TT, Kc=0.36K_c = 0.36 and RT=24.5RT = 24.5 LΒ·atm/mol. Find KpK_p.

Example 18

easy
A reaction has K=1Γ—10βˆ’8K = 1 \times 10^{-8}. Are products or reactants favored at equilibrium?

Example 19

easy
KpK_p uses ____ instead of concentrations for gaseous species.

Example 20

easy
Write KcK_c for 3Aβ‡ŒB3A \rightleftharpoons B.
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