Question

The half-life times for a reaction at initial concentrations of 0.1 mol/L and 0.4 mol/L are 200 s and 50 s, respectively. The order of the reaction is:

• A. 0
• B. 1
• C. 2
• D. 3

Hint:

Form the ratio of half-lives and concentrations, then solve for n.

Answer 1

The Correct Option is C

Step 1: t1/2 proportional to [A]0^(1-n).

Step 2: 200/50 = (0.1/0.4)^(1-n) => 4=(0.25)^(1-n).

Step 3: log4=(1-n)log0.25 => 1-n=-1 => n=2.

\[\boxed{\text{Order} = 2}\]