Question

Which of the following statements is true about the equilibrium constant and rate constant of a single-step chemical reaction?

• A. Equilibrium constant may increase or decrease, but rate constant always increases with temperature.
• B. Both equilibrium constant and rate constant increase with temperature
• C. Rate constant may increase or decrease, but equilibrium constant always increases with temperature.
• D. Both equilibrium constant and rate constant decrease with temperature

Answer 1

The Correct Option is A

• The rate constant (k) is governed by the Arrhenius equation:
• The equilibrium constant (K) depends on the reaction’s enthalpy change (\(\Delta H\)):
  Thus, the equilibrium constant can either increase or decrease depending on the reaction’s nature, but the rate constant always increases with temperature.

Answer 2

Correct Answer:

Option 1: Equilibrium constant may increase or decrease, but rate constant always increases with temperature.

Explanation:

Rate Constant (k):

The rate constant (k) is related to temperature by the Arrhenius equation: k = A * e^(-Ea/RT).

As temperature (T) increases, the rate constant (k) always increases.

Equilibrium Constant (K):

The equilibrium constant (K) is related to the rate constants of the forward and reverse reactions: K = k_f / k_r.

The temperature dependence of K is given by the van 't Hoff equation: d(ln K)/dT = ΔH°/RT².

• If ΔH° > 0 (endothermic), K increases with temperature.
• If ΔH° < 0 (exothermic), K decreases with temperature.

Therefore, the equilibrium constant can either increase or decrease, depending on the reaction.