In first order reaction, the concentration of reactant decreases from 800 mol cm -3 to 50 mol/ dm -3 in 2 × 104 s. The rate constant is

Question

In first order reaction, the concentration of reactant decreases from 800 mol cm -3 to 50 mol/ dm -3 in 2 × 104 s. The rate constant is (A)  2× 104s-1 (B) 3.45 × 10-5 s-1 (C) 1.386 × 10-4 s -1 (D) 2 × 10-4 s-1

Tardigrade Admin · Accepted Answer

For first order reaction, Rate constant, k=(2.303/t) log (a/a-x) ⇒ k=(2.303/2 × 104) log (800/50) =1.386 × 10-4 s-1

Q. In first order reaction, the concentration of reactant decreases from $800 m o l c m^{- 3}$ to $50 m o l / d m^{- 3}$ in $2 \times 1 0^{4} s$ . The rate constant is

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

$3.45 \times 1 0^{- 5} s^{- 1}$

$1.386 \times 1 0^{- 4} s^{- 1}$

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

For first order reaction, Rate constant,
$k = \frac{2.303}{t} lo g \frac{a}{a - x}$
$\Rightarrow k = \frac{2.303}{2 \times 1 0 ^{4}} lo g \frac{800}{50}$
$= 1.386 \times 1 0^{- 4} s^{- 1}$

Q. In first order reaction, the concentration of reactant decreases from 800molcm−3 to 50mol/dm−3 in 2×104s. The rate constant is

2×104s−1

3.45×10−5s−1

1.386×10−4s−1

2×10−4s−1