Consider the rate law. cap A plus 3 cap b rightarrow 2 cap c plus 2 cap d The rate increases by a factor of 9 when the concentration of cap A triples.The rate triples when the concentration of cap b triples. What is the new rate law for the reaction?

Write the rate law as r = k[A]^m[B]^n. When [A] triples, the rate increases by 9, so 3^m = 9 and m = 2. When [B] triples, the rate triples, so 3^n = 3 and n = 1. Therefore, the rate law is r = k[A]^2[B], choice A.

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