5% Rule

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Seohyun Park 1L
Posts: 73
Joined: Fri Sep 28, 2018 12:29 am

5% Rule

Postby Seohyun Park 1L » Wed Jan 23, 2019 9:11 am

Does the 5% Rule for approximation only apply to acid/base reactions in water? Can we use the approximation technique for small K values for equilibrium problems not involving acid/base?

Tarika Gujral 1K
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

Re: 5% Rule

Postby Tarika Gujral 1K » Wed Jan 23, 2019 11:14 am

The 5% approximation technique can be used for any K calculation, provided

K < 10-3 — Very little product formed, R-x = R
K > 103 — Very little reactant remaining, P+x = P

Irene Zhou 1E
Posts: 73
Joined: Fri Sep 28, 2018 12:18 am

Re: 5% Rule

Postby Irene Zhou 1E » Wed Jan 23, 2019 8:19 pm

The 5% ionization approximation can be applied to any K calculation as long as K is less that 10^-3

juliasloan_4g
Posts: 67
Joined: Fri Sep 28, 2018 12:28 am

Re: 5% Rule

Postby juliasloan_4g » Wed Jan 23, 2019 9:10 pm

the 5 percent rule can be used in any calculation of K

sophiebillings1E
Posts: 60
Joined: Fri Sep 28, 2018 12:27 am

Re: 5% Rule

Postby sophiebillings1E » Wed Jan 23, 2019 10:54 pm

But if you do disregard x make sure to double check that it is under 5% because if not the solution is incorrect.

Jasmine Chow 1F
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am
Been upvoted: 1 time

Re: 5% Rule

Postby Jasmine Chow 1F » Thu Jan 24, 2019 1:41 pm

you can use the 5% rule for a K value that is less than 10^-3 for acids and bases or equilibrium concentrations and pressures.


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