Sig Figs of pKa

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Olivia L 4E
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Joined: Fri Sep 28, 2018 12:23 am
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Sig Figs of pKa

Postby Olivia L 4E » Tue Jan 22, 2019 11:53 am

The number of significant figures in pH is equal to the number of digits after the decimal point, I was just wondering if this was the same rule for pKa? I didn't think so but my book solutions keep following that rule. Then again, my 7th edition tends to use the wrong sig figs frequently.

Emma Scholes 1L
Posts: 62
Joined: Fri Sep 28, 2018 12:18 am

Re: Sig Figs of pKa

Postby Emma Scholes 1L » Tue Jan 22, 2019 12:34 pm

It is the same rule for pKa because the rule applies whenever you take the log of something.

Cole Elsner 2J
Posts: 88
Joined: Fri Sep 28, 2018 12:25 am

Re: Sig Figs of pKa

Postby Cole Elsner 2J » Tue Jan 22, 2019 2:22 pm

This applies to pKa and pKb as well because a log is being taken. If you try to use 10^-pKa/b, you will not get the concentration you initially had, so this rule remains.

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