## 1/2 life

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

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Tatum Keichline 2B
Posts: 64
Joined: Fri Sep 28, 2018 12:26 am

### 1/2 life

Does the 1/2 life for first order depend on the initial concentration like it does for zero and second-order reactions?

David Effio 1H
Posts: 38
Joined: Wed Feb 14, 2018 3:01 am

### Re: 1/2 life

No, if you look at the equation, the half-life only takes into account the rate constant, which is dependent on temp and activation energy only.

Rachel-Weisz3C
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Joined: Fri Sep 28, 2018 12:23 am

### Re: 1/2 life

1/2 life for first order is the only order that is not dependent on initial concentration but just the reaction constant (k), with units 1/s.

Danielle_Gallandt3I
Posts: 70
Joined: Fri Sep 28, 2018 12:24 am

### Re: 1/2 life

No, based on the half-life equations it is not affected by initial concentration, only the rate constant. This means that the half life is actually more dependent on other factors, such as temperature

SydBenedict2H
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Joined: Wed Nov 08, 2017 3:00 am

### Re: 1/2 life

Why is it that for only the first order it isn't dependent on the initial concentration?

Raj_Bains_2C
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### Re: 1/2 life

The half-life for first order dow not depend on the initial concentration.

Raj_Bains_2C
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### Re: 1/2 life

Raj_Bains_2C wrote:The half-life for first order dow not depend on the initial concentration.

*does not*

Casandra
Posts: 65
Joined: Fri Sep 28, 2018 12:17 am

### Re: 1/2 life

The 1/2 life for a first order does not depend on the initial concentration.

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