Question #1d00a

1 Answer
Sep 15, 2016

Here's how to think about it.

Since a plot of 1/P_"A" vs. t is linear, the reaction is second-order in "A".

Therefore, you use the equations for a second-order reaction.

The integrated rate law for a second order reaction is

color(blue)(bar(ul(|color(white)(a/a) 1/"A"_t = kt + 1/"A"_0color(white)(a/a)|)))" "

where "A" represents the pressure of the gas.

The slope of the plot of 1/"A"_t vs t is k.

For a second order reaction,

color(blue)(bar(ul(|color(white)(a/a) t_½ = 1/(k"A"_0) color(white)(a/a)|)))" "

Since you now know the values of k and "A"_0, you can calculate the half-life.

If "A"_0 = 150 ppbv, 10 % of "A"_0 = 15.0 ppbv.

Insert these values into the integrated rate law and solve for t.