question_answer 11)

For the reaction : 2A + B  A2B the rate = k [A] [B]2 with k = 2.0 x 10?6 mol ?2 L2 s?1. Calculate the initial rate of the reaction when [A] = mol L?1, [B] = 0.2 mol L?1.  Calculate the rate of reaction after [A] is reduced to 0.06 mol L?1.

Answer:

K = 2.0 × 10?6 mol?2 L2 s?1 [A] = 0.1 mol L?1, [B] = 0.2 mol L?1 r = k [A] [B]2 = 2.0 × 10?6 mol?2L2 s?1 × 0.1 mol L?1 × 0.2 mol L?1 × 0.2 mol L?1 = 8.0 × 10?9 mol L?1 s?1. when r = 2.0 × 10?6 × 0.06 × (0.2)2 = 4.8 × 10‑9 mol L?1 s?1