Question

For a reaction $R \to P$, the concentration of a reactant changes from $0.05\, M$ to $0.04 \,M$ in $30$ minutes. What will be the average rate of reaction in minutes?

• A. $4 \times 10^{-4} M \,min^{-1}$
• B. $8 \times 10^{-4} M\, min^{- 1}$
• C. $3.3 \times 10^{-4} \, M \, min^{-1}$
• D. $2.2 \times 10^{-4} \, M \, min^{-1}$

Answer 1

Answer: (C)

Average rate $=-\frac{\Delta[R]}{\Delta t}=-\frac{([R]_{2}-[R]_{1})}{t_{2}-t_{1}}$
$=-\frac{(0.04-0.05)}{30}=\frac{0.01}{30}$
$=3.3\times10^{-4} M \, min^{-1}$