Question

Consider the reaction 2A + B →products, when the concentration of A alone was doubled, the half-life of the reaction did not change. When the concentration of B alone was doubled, the rate was not altered. The unit of rate constant for this reaction is

• A. (A) s − 1
• B. (B) L mol − 1 s − 1
• C. (C) mol L − 1 s − 1
• D. (D) mol − 2 L5 s − 1

Answer 1

Answer: (A)

(A) s − 1

Answer 2

Explanation:
2A+B→ ProductLet rate of reaction, r=k[A]x1[B]x2When concentration of B doubled rate does not changesSo, r1=r2⇒k[A]x1[B]x2=k[A]x1[2B]x2⇒[B]x2=[2B]x2⇒x2=0so rate, r=k[A]x1Now when Concentration of A doubled half life does not changeit means reaction is first order so x1=1and r=k{A]order of reaction =1so unit of rate constant =s−1