The rate of disappearance of SO2 in the reaction 2SO2+O2→2SO3 is 1.28×10−3 M/sec then the rate of formation of SO3 is

A
$0 .64 \times 10^{- 3} M / \sec$
B
$0 .80 \times 10^{- 3} M / \sec$
C
$1 .28 \times 10^{- 3} M / \sec$
D
$1 .60 \times 10^{- 3} M / \sec$

Solution:

The rate of formation of ${SO}_{3}$ is $1.28 \times 10^{- 3} M/sec$

$\begin{array}{l} \frac{- d [{SO}_{2}]}{dt} = 1 .28 \times 10^{- 3} \\ r = - \frac{1}{2} \frac{d [{SO}_{2}]}{dt} = \frac{1}{2} \frac{d [{SO}_{3}]}{dt} = - \frac{d [O_{2}]}{dt} \\ \Rightarrow - \frac{1}{2} \frac{d [{SO}_{2}]}{dt} = \frac{1}{2} \frac{d [{SO}_{3}]}{dt} \\ \Rightarrow \frac{d [{SO}_{3}]}{dt} = 1 .28 \times 10^{- 3} \end{array}$