Question

For a given first order reaction, the following graph is obtained :
$A\to \text{products}$
The slope of the graph is found out to be $-2$

The time (t) is taken in minutes.
The value of rate constant is :

• A. $2.303mi{n}^{-1}$
• B. $4.606mi{n}^{-1}$
• C. $0.3010mi{n}^{-1}$
• D. $2mi{n}^{-1}$

Answer 1

The correct option is B $4.606mi{n}^{-1}$

Since ,
$ln\frac{[A{]}_0}{\left[A\right]}=kt$
$\frac{2.303}{t}log\frac{[A{]}_0}{\left[A\right]}=k$
$log\left[A\right]=log[A{]}_0-\frac{kt}{2.303}$
From the graph , the slope is:
$-\frac{k}{2.303}=-2$ (given)

$k=4.606mi{n}^{-1}$