## 5% approximation rule

Hannah Lee 2F
Posts: 117
Joined: Thu Jul 11, 2019 12:15 am

### 5% approximation rule

As a general rule of thumb, can we assume the approximation rule whenever K < 10^-5 or K < 10^-3? Which value of K is it? (assuming that you always check if the approximation is valid after solving for x)

BCaballero_4F
Posts: 94
Joined: Wed Nov 14, 2018 12:22 am

### Re: 5% approximation rule

I believe it is anything less than 10^-3

Amir Bayat
Posts: 115
Joined: Sat Sep 07, 2019 12:16 am

### Re: 5% approximation rule

Anything less than 10^-3 is a valid use of approximation if the percent ionization/protonization/deprotonization is less than 5%.

Hailey Kim 4G
Posts: 110
Joined: Sat Jul 20, 2019 12:16 am

### Re: 5% approximation rule

Hannah Lee 2F wrote:As a general rule of thumb, can we assume the approximation rule whenever K < 10^-5 or K < 10^-3? Which value of K is it? (assuming that you always check if the approximation is valid after solving for x)

How do you check if the approximation is valid? Do you look at what you solved for x and see if it is less than 5% or do you look at the percent protonated/deprotonated and see if it is less than 5%?

Kaylee Clarke 1G
Posts: 103
Joined: Fri Aug 30, 2019 12:15 am

### Re: 5% approximation rule

Dr.Lavelle said it is 10^-3.

Jasmine Vallarta 2L
Posts: 102
Joined: Sat Aug 17, 2019 12:18 am

### Re: 5% approximation rule

< 10^-3

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