Question

For a generic reaction:
$2A\to B$
The rate of appearance of $B$ is recorded as $3.5\times {10}^{-2}M/s$.
What is the rate of disappearance of $A$?

• A. $-7.0\times {10}^{-2}M/s$
• B. $-3.5\times {10}^{-2}M/s$
• C. $3.5\times {10}^{-2}M/s$
• D. $7.0\times {10}^{-2}M/s$

Answer 1

Answer: (D)

$7.0\times {10}^{-2}M/s$

Rates of A and B can be given by : $-\frac{1}{2}\frac{dA}{dt}=\frac{dB}{dt}$

For the given reaction rate of disappearance is $-\frac{dA}{dt}$

So, $-\frac{dA}{dt}=2\times 3.5\times {10}^{-2}M/s$

$⟹\frac{-dA}{dt}=7.0\times {10}^{-2}M/s$