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) are:

• 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)

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

here, $t_{1/2}\propto$ a. Hence, 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 = $t_{10\%}=10min,x=10,$
Then, k = $\frac{10}{10}=1mol{L}^{-1}h{r}^{-1}$
If t = $t_{20\%}=20min,x=20,$
Then, k = $\frac{20}{20}=1mol{L}^{-1}h{r}^{-1}.$
Similarly, for $30$% and so on.
Thus, reaction is of zero order.