Question

Average rate of reaction $2\, SO_2 \,{(g)} + O_2{\, (g)} ⎯⎯→ 2 \,SO_3{\, (g)}$ is written as

• A. $\frac{\Delta\left[SO_{2}\right]}{\Delta t}$
• B. $-\frac{\Delta\left[O_{2}\right]}{\Delta t}$
• C. $\frac{1}{2}\frac{\Delta\left[SO_{2}\right]}{\Delta t}$
• D. $\frac{\Delta\left[SO_{3}\right]}{\Delta t}$

Answer 1

Answer: (B)

Average rate of reaction is defined as the speed with which the reactants are converted into products.

For reaction,

$2 SO _{2}(g)+ O _{2}(g) \longrightarrow 2 SO _{3}(g)$

$-\frac{1}{2} \frac{\Delta\left[ SO _{2}\right]}{\Delta t}=\frac{-\Delta\left[ O _{2}\right]}{\Delta t}$

$=+\frac{1}{2} \frac{\Delta\left[ SO _{3}\right]}{\Delta t}$

So, average rate of reaction is written as

$-\frac{\Delta\left[ O _{2}\right]}{\Delta t}.$