Question

At 500 K, the half life period of a gaseous reaction at an initial pressure of 80 kPa is 350 s. When the pressure is 40 kPa, the half life period is 175 sec; the order of the reaction is

• A. Zero
• B. One
• C. Two
• D. Three

Answer 1

Answer: (A)

Zero

Answer 2

$\frac{(t_{1/2})_{1}}{(t_{1/2})_{2}}$ = $\left( \frac{p_{2}}{p_{1}} \right)^{n - 1}$

$\frac{350}{175}$ = $\left( \frac{40}{80} \right)^{n - 1}$

2 = $\left( \frac{1}{2} \right)^{n - 1}$

n – 1 = – 1

n = 0 (zero order reaction)