For the endothermic first-order reaction $A B$ , $E_{a, f} = 80$ and $Δ H = + 30 kJ mo l^{- 1}$ . A catalyst lowers $E_{a, f}$ to $60 kJ mo l^{- 1}$ at fixed pre-exponential factors. Select the correct statement(s).

Answer: A, B, C

Δ H = E_{a, f} - E_{a, r}

is unchanged, so

E_{a, r} = 60 - 30 = 30

with the catalyst (before:

80 - 30 = 50

). Both rate constants increase because both activation energies drop by

20 kJ mo l^{- 1}

, and

K = k_{f} / k_{b}

is therefore unchanged.

Δ H

stays

+ 30

, so the last statement is false.