Half life
Moderators: Chem_Mod, Chem_Admin
-
- Posts: 104
- Joined: Sat Sep 07, 2019 12:19 am
-
- Posts: 103
- Joined: Sat Aug 24, 2019 12:15 am
Re: Half life
to find the half life of the zero order reaction, you need to use the equation [A.5]=-kt+[A0], where A.5 is half the concentration of A0
+
+
-
- Posts: 100
- Joined: Wed Sep 30, 2020 9:53 pm
- Been upvoted: 1 time
-
- Posts: 112
- Joined: Wed Sep 30, 2020 9:38 pm
Re: Half life
Today in lecture (3/3) Dr. Lavelle went through the derivation of finding the equation for the half-life of a zero-order reaction.
He started with the equation , then when looking for we know that . Then we can find that
which simplifies to and ultimately gives us the zero-order half life equation which is:
He started with the equation , then when looking for we know that . Then we can find that
which simplifies to and ultimately gives us the zero-order half life equation which is:
-
- Posts: 105
- Joined: Wed Sep 30, 2020 9:39 pm
-
- Posts: 108
- Joined: Wed Sep 30, 2020 10:05 pm
- Been upvoted: 1 time
Re: Half life
The half life of a zero order reaction is
The derivation of this equation was in 3/3 lecture. The integrated rate law for the zero order is . At , [A] = 1/2*([A]_0). When we substitute 1/2[A]_0 into the equation for [A], the equation can be rearranged. The initial concentrations of A can be combined and then we solve for . When we solve for , we get the half life equation for the zero order.
We can either derive the equation every time you want to use the half life equation for each order, using its specific integrated rate law, or you can use the answer of the derivation. The half life equation will be the same for every problem that is of that order.
The derivation of this equation was in 3/3 lecture. The integrated rate law for the zero order is . At , [A] = 1/2*([A]_0). When we substitute 1/2[A]_0 into the equation for [A], the equation can be rearranged. The initial concentrations of A can be combined and then we solve for . When we solve for , we get the half life equation for the zero order.
We can either derive the equation every time you want to use the half life equation for each order, using its specific integrated rate law, or you can use the answer of the derivation. The half life equation will be the same for every problem that is of that order.
-
- Posts: 100
- Joined: Wed Sep 30, 2020 10:01 pm
-
- Posts: 122
- Joined: Wed Sep 30, 2020 9:59 pm
Re: Half life
To begin, Half life is when the reaction reaches half the initial amount. Hence, 0.5A=-kt+A. Then becomes -.5A=-kt which more so .5A=kt. So then we get A*1/(2*k)=t. That the half life of zero reaction.
-
- Posts: 103
- Joined: Wed Sep 30, 2020 9:41 pm
-
- Posts: 131
- Joined: Thu Jul 25, 2019 12:16 am
Re: Half life
You must use the specific half life equation for a zero order reaction which is t1/2 = [A]0/2k
-
- Posts: 116
- Joined: Wed Sep 30, 2020 9:39 pm
-
- Posts: 100
- Joined: Wed Sep 30, 2020 10:07 pm
Re: Half life
we use the equation specifically for half life for zero order reactions! which is the equation everyone else has stated
-
- Posts: 100
- Joined: Wed Sep 30, 2020 9:50 pm
-
- Posts: 50
- Joined: Wed Nov 20, 2019 12:20 am
Re: Half life
I believe you can use the half-life equation where you divide [A]/2k. The first step is to find the original concentration of the given molecule.
-
- Posts: 109
- Joined: Fri Sep 24, 2021 5:23 am
Re: Half life
In order to determine the half-life of a reaction, you can begin by using this equation:
t1/2 = [A]0/2k
t1/2 = [A]0/2k
Return to “Zero Order Reactions”
Who is online
Users browsing this forum: No registered users and 2 guests