Question

The rate of a first order reaction is $1.8 \times 10^{-3}\, mol\, L ^{-1}$ $\min ^{-1}$ when the initial concentration is $0.3\, mol\, L ^{-1}$. The rate constant is

• A. $1 \times 10^{-2} s ^{-1}$
• B. $1 \times 10^{-4} s ^{-1}$
• C. $6 \times 10^{-2} s ^{-1}$
• D. $4 \times 10^{-4} s ^{-1}$

Answer 1

Answer: (B)

Rate $= k [ A ]$

$1.8 \times 10^{-3}\, mol\, L ^{-1}\, \min -1= k \times 0.3\, mol\, L ^{-1}$

$\therefore k =\frac{1.8 \times 10^{-3}}{0.3 \times 60}=1 \times 10^{-4} s ^{-1}$