Question

In the first order thermal decomposition of $C _{2} H _{5} I (g) \longrightarrow C _{2} H _{4}(g)+ HI (g)$, the reactant in the beginning exerts a pressure of $2$ bar in a closed vessel at $600 \,K$. If the partial pressure of the reactant is $0.1$ bar after $1000$ minutes at the same temperature the rate constant in $\min ^{-1}$ is $(\log 2=0.3010)$

• A. $6.0 \times 10^{-4}$
• B. $6.0 \times 10^{- 3}$
• C. $3 .0 \times 10^{- 3}$
• D. $3.0 \times 10^{-4}$

Answer 1

The Correct Option is C

Since, the reaction is first order,

$k= \frac{2.303}{t} \log \frac{p}{p_{0}-x} $

$k =\frac{2.303}{1000} \log \frac{2}{2-1.9} $

$=\frac{2303}{1000} \log 20$

$k =3 \times 10^{-3} \min ^{-1}$