# In a reaction, 2A → Products,

Question:

In a reaction, 2A  Products, the concentration of A decreases from 0.5 mol L−1 to 0.4 mol L−1 in 10 minutes. Calculate the rate during this interval?

Solution:

Average rate $=-\frac{1}{2} \frac{\Delta[\mathrm{A}]}{\Delta t}$

$=-\frac{1}{2} \frac{[\mathrm{A}]_{2}-[\mathrm{A}]_{1}}{t_{2}-t_{1}}$

$=-\frac{1}{2} \frac{0.4-0.5}{10}$

$=-\frac{1}{2} \frac{-0.1}{10}$

= 0.005 mol L−1 min−1

= 5 × 10−3 M min−1