AP Chemistry: Kinetics & Chemical Equilibrium 3

Question 1

For the equilibrium N2(g) + 3H2(g) ⇌ 2NH3(g), what is the correct expression for Kc?

Accepted Answer

[NH3]^2 / ([N2][H2]^3)

Answer

Kc places products over reactants, each raised to its stoichiometric coefficient.

Question 2

If Q < K for a reaction, the system will

Accepted Answer

shift toward products

Answer

When Q < K, the reaction proceeds forward to form more products until Q = K.

Question 3

For an exothermic reaction at equilibrium, increasing temperature will

Accepted Answer

shift toward reactants and decrease K

Answer

Adding heat to an exothermic reaction shifts equilibrium toward reactants, lowering K.

Question 4

Decreasing the volume of a gaseous equilibrium system shifts the reaction toward

Accepted Answer

the side with fewer moles of gas

Answer

Increasing pressure by reducing volume shifts equilibrium toward fewer gas moles.

Question 5

Which change does NOT alter the value of the equilibrium constant K?

Accepted Answer

Adding a catalyst

Answer

Only temperature changes K; a catalyst speeds equilibrium but leaves K unchanged.

AP Practice Test