What is the rate when the initial concentration of A = 1.67 mol/L and that of B = 1.18 mol/L

Question

For the reaction, A(g) + B(g) => AB(g), the rate is 0.417 mol/L.s when the initial concentrations of both A and B are 2.00 mol/L. If the reaction is first order in A and second order in B, what is the rate when the initial concentration of A = 1.67 mol/L and that of B = 1.18 mol/L  Give answer to 2 decimal places.

(answer is 0.12)

Answer 1

Rate = k[A][B]²

k = rate/ [A][B]² = 0.417/(2)(2)²

k = 0.052

rate = 0.052 (1.67)(1.18)² = 0.12 mol/Ls