sapling #11 week 9/10

[LexyDenaburg_3A]

Hi, can someone explain how to solve for this question, I've been struggling.

Dinitrogen pentoxide, N2O5, decomposes by first‑order kinetics with a rate constant of 3.7×10−5 s−1 at 298 K.
What is the half‑life, in hours, of N2O5 at 298 K?
If [N2O5]0=0.0512 mol⋅L−1, what will be the concentration of N2O5 after 3.0 h?
How much time, in minutes, will elapse before the N2O5 concentration decreases from 0.0512 mol⋅L−1 to 0.0166 mol⋅L−1?

[Joyce Pang 2H]

For the first part, we're told it's a first-order reaction, so we can just plug in the given values into the half-life equation for first order, t=0.693/k. That'll give us an answer in seconds, so we just have to convert that into hours by dividing 3600.

For the second part, we're given an initial concentration and a half life, so we'll plug that into the first order reaction equation [A]=[Ainitial]*e^-kt. The rest is just solving.

For the third part, we do the same as above, except this time, we're solving for time, and then converting it into minutes.