Chemistry: Kinetics & Chemical Equilibrium Flashcards

A proposed mechanism has a slow first step followed by a fast step. The rate law is determined by

Answer: the slow step

The rate-determining (slowest) step controls the overall rate law.

An intermediate in a reaction mechanism is a species that is

Answer: produced in one step and consumed in a later step

Intermediates are formed and then consumed during the mechanism, not appearing in the overall equation.

Kp and Kc are related by Kp = Kc(RT)^Δn. For N2 + 3H2 ⇌ 2NH3, Δn equals

Answer: -2

Δn = moles gas products (2) minus moles gas reactants (4) = -2.

For a zero-order reaction, the rate is

Answer: independent of [A]

A zero-order rate is constant and does not depend on reactant concentration.

In a reaction energy diagram, the activation energy is the difference between the

Answer: reactant energy and the transition-state peak

Forward activation energy is measured from reactants up to the transition-state peak.

If the forward reaction is endothermic, the reverse activation energy compared to the forward is

Answer: smaller

For an endothermic reaction the reverse activation energy is smaller than the forward.

The overall order of a reaction with rate = k[A][B]^2 is

Answer: 3

Overall order is the sum of the exponents: 1 + 2 = 3.