In a first order reaction, the concentration of reactant decreases from 400 mol L-1 to 25 mol L-1 in 200 seconds. The rate constant for the reaction is

Question

In a first order reaction, the concentration of reactant decreases from 400 mol L-1 to 25 mol L-1 in 200 seconds. The rate constant for the reaction is (A) 1.0386 s-1 (B) 2×10-4 s-1 (C) 1.386×10-2 s-1 (D) 3.4×10-4 s-1

Tardigrade Admin · Accepted Answer

For first order reaction, k=(2.303/t) log (a/(a-x))=(2.303/200) log (400/25) =(2.303/200)×1.204 =0.01386 s-1 =1.386×10-2 s-1

Q. In a first order reaction, the concentration of reactant decreases from $400 m o l$ $L^{- 1}$ to $25 m o l$ $L^{- 1}$ in $200$ seconds. The rate constant for the reaction is

$1.0386$ $s^{- 1}$

$2 \times 1 0^{- 4}$ $s^{- 1}$

$1.386 \times 1 0^{- 2}$ $s^{- 1}$

$3.4 \times 1 0^{- 4}$ $s^{- 1}$

For first order reaction,
$k = \frac{2.303}{t} l o g$ $\frac{a}{( a - x )} = \frac{2.303}{200} l o g$ $\frac{400}{25}$
$= \frac{2.303}{200} \times 1.204$ $= 0.01386$ $s^{- 1}$ $= 1.386 \times 1 0^{- 2}$ $s^{- 1}$

Q. In a first order reaction, the concentration of reactant decreases from 400mol L−1 to 25mol L−1 in 200 seconds. The rate constant for the reaction is

1.0386 s−1

2×10−4 s−1

1.386×10−2 s−1

3.4×10−4 s−1