Question

In a reaction $2X \to Y$, the concentration of $X$ decreases from $3.0$ moles/litre to $2.0$ moles/litre in $5$ minutes. The rate of reaction is

• A. $0.1\, mol\, L^{-1} min^{-1}$
• B. $5\, mol\, L^{-1} min^{-1}$
• C. $1 \,mol\, L^{-1} min^{-1}$
• D. $0.5\, mol\, L^{-1} min^{-1}$

Answer 1

Answer: (A)

Rate $=-\frac{1}{2} \frac{\Delta\left[X\right]}{\Delta t}$
$=-\frac{1}{2}\frac{\left(3-2\right)}{5}=-0.1 \,mol\, L^{-1} min^{-1}$
Negative sign signifies the decrease in concentration.