Observe the following reactions at T(K). I. A products. II. 5Br-(aq) + BrO3-(aq) + 6H+(aq) 3Br2(aq) + 3H2O(l) Both the reactions are started at 10.00 am. The rates of these reactions at 10.10 am are same. The value of - [Br-] t at 10.10 am is 2 10-4 mol L-1 min-1. The concentration of A at 10.10 am is 10-2 mol L-1. What is the first order rate constant (in min-1) of reaction I?
- 4 10-3
- 2 10-3
- 10-3
- 10-2
Answer
(1) 4 10-3
Solution
The rate of reaction II is - 15 [Br-] t, so
Rate = 2 10-45 = 4 10-5 mol L-1 min-1
At 10.10 am the rate of reaction I equals this rate, and for the first order reaction I, Rate = k[A], so
4 10-5 = k 10-2
k = 4 10-3 min-1
Answer: (1)