Question

In a certain reaction, 10% of the reactant decomposes in one hour, 20% in two hours, 30% in three hours, and so on. The dimension of the velocity constant (rate constant) is:

• A. $H{r}^{-1}$
• B. $Mol{L}^{-1}h{r}^{-1}$
• C. $Lmo{l}^{-1}{s}^{-1}$
• D. $Mol{s}^{-1}$

Answer 1

Answer: (B)

$Mol{L}^{-1}h{r}^{-1}$

For zero-order reaction rate is independent of concentration. Hence, it is a zero-order reaction. So, dimension of $k=$ $mol{L}^{-1}h{r}^{-1}$

For zero order: t $=\frac{x}{k}ork=\frac{x}{t}$

If t $=t_{10\%}=60min,x=10,$

Then, r $=\frac{-10}{1}=10mol{L}^{-1}h{r}^{-1}$

If t $=t_{20\%}=120min,x=20,$

Then, r $=\frac{20}{2}=10mol{L}^{-1}h{r}^{-1}.$

Similarly, for 30% and so on.

Thus, the reaction is of zero order.