## Half Life Equations

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

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Jada Brown 2H
Posts: 100
Joined: Sat Aug 17, 2019 12:15 am

### Half Life Equations

Do we need to memorize the half life equations for zeroth and second order rate laws? Will they be given on the equation sheet for the final?

Nohemi Garcia 1L
Posts: 103
Joined: Fri Aug 02, 2019 12:15 am

### Re: Half Life Equations

I'm pretty sure they were written on our tests last week so it's likely that they'll be provided. It doesn't hurt to memorize them though.

Leslie Almaraz 4G
Posts: 99
Joined: Fri Aug 02, 2019 12:16 am

### Re: Half Life Equations

I think they will be provided!

Maika Ngoie 1B
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Joined: Fri Aug 02, 2019 12:16 am

### Re: Half Life Equations

They should be provided, but it may be easier to memorize which equation goes with which order.

Prasanna Padmanabham 4I
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Joined: Thu Jul 25, 2019 12:17 am

### Re: Half Life Equations

It's an open book final...

Luc Zelissen 1K
Posts: 57
Joined: Mon Jun 17, 2019 7:23 am

### Re: Half Life Equations

For Zero Order reaction: t½ = [Ao] / 2k
For First Order reaction: t½ = 0.693 / k
For Second Order Reaction: t½ = 1 / k [Ao]

They are given, but they are not labeled on the constants sheet.

Tanmay Singhal 1H
Posts: 143
Joined: Sat Jul 20, 2019 12:16 am

### Re: Half Life Equations

i'm pretty sure they will be given but the final is also open book

Keya Jonnalagadda 1A
Posts: 50
Joined: Mon Jun 17, 2019 7:24 am

### Re: Half Life Equations

As the final is open-book, this shouldn't be a concern anymore, but the homework question (7A.7 I believe) that discusses the units of the rate constant for different rate orders is good to review on this topic.

Alfred Barrion 2H
Posts: 100
Joined: Sat Jul 20, 2019 12:16 am

### Re: Half Life Equations

They are typically provided on the list of given equations!

Maggie Eberhardt - 2H
Posts: 97
Joined: Sat Jul 20, 2019 12:16 am

### Re: Half Life Equations

can someone explain their importance/use?

Samuel G Rivera - Discussion 4I
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Joined: Sat Aug 17, 2019 12:16 am
Been upvoted: 1 time

### Re: Half Life Equations

The 0th, 1st, and 2nd order equations are provided on the equation sheet but the equation sheet doesn't specify which one is which. So if you are doing your test with the equation sheet I recommend labeling each one so you don't mix them up.

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