Question

$aA+bB⟶P$; $dx/dt=k{\left[A\right]}^a\cdot {\left[B\right]}^b$. If conc. of $A$ is doubled, rate is doubled. If $B$ is doubled, rate becomes four times. Which of the following is correct?

• A. $\frac{-d\left[A\right]}{dt}=\frac{-d\left[B\right]}{dt}$
• B. $\frac{-d\left[A\right]}{dt}=\frac{-2d\left[B\right]}{dt}$
• C. $\frac{-2d\left[A\right]}{dt}=\frac{-d\left[B\right]}{dt}$
• D. None of the above

Answer 1

Answer: (C)

$\frac{-2d\left[A\right]}{dt}=\frac{-d\left[B\right]}{dt}$

$a=1,b=2$

Thus,

$-\frac{2d}{dt}\left[A\right]=-\frac{d}{dt}\left[B\right]$