The reaction 2X → B is a zeroth order reaction. If the initial concentration of X is 0.2 M, the half-life is 6 h. When the initial concentration of X is 0.5 M, the time required to reach its final concentration of 0.2 M will be :

Question

The reaction 2X → B is a zeroth order reaction. If the initial concentration of X is 0.2 M, the half-life is 6 h. When the initial concentration of X is 0.5 M, the time required to reach its final concentration of 0.2 M will be : (A) 18.0 h (B) 7.2 h (C) 9.0 h (D) 12.0 h

Tardigrade Admin · Accepted Answer

For zero order [A0 ] -[At] =kt 0.2 - 0.1 = k × 6 k = (1/60) M/hr and 0.5 - 0.2 = (1/60) × t t = 18 hrs.

Q. The reaction $2 X \to B$ is a zeroth order reaction. If the initial concentration of $X$ is $0.2 M$ , the half-life is $6 h$ . When the initial concentration of $X$ is $0.5 M$ , the time required to reach its final concentration of $0.2 M$ will be :

18.0 h

7.2 h

9.0 h

12.0 h

For zero order
$[A_{0}] - [A_{t}] = k t$
$0.2 - 0.1 = k \times 6$
$k = \frac{1}{60} M / h r$
and $0.5 - 0.2 = \frac{1}{60} \times t$
$t = 18 h rs$ .

Q. The reaction 2X→B is a zeroth order reaction. If the initial concentration of X is 0.2M, the half-life is 6h. When the initial concentration of X is 0.5M, the time required to reach its final concentration of 0.2M will be :