Half Lives? [ENDORSED]

[Hellen Truong 2J]

Is it accurate to use half lives for questions that say something like 1/4 of the reactant is remaining?

[Christine Wastila 1H]

Yes because that would indicate that the species has undergone two half-lives.

[skalvakota2H]

In general, at any stage of the reaction, we can find how much of a reactant is remaining after n half-lives by (1/2)^n [A]0. Thus, if 1/2 is a factor of the remaining amount, then it is allowed to use the half life method.

[CalebBurns3L]

Yes, you would simply calculate the half life and then multiple it by 2 get the time to reach 1/4 of the reactant remaining.

[Ilan Shavolian 1K]

yes because 1/4th product is = the amount left after two half lives

[Fatima_Iqbal_2E]

Yes, because you would be able to multiply the half-life by the number of times it occurred to find the time it would take to reach the new concentration.

[snehabhargava]

yes, because 1/4 is the half life of the half life.

[Timothy Kim 1B]

Yes, half-life works for that fraction.