Question about Casio FX-115MS Plus Calculator
How do I find the pka value using my calculator. What buttons do I press?
If I guessed right you are talking about the Chemistry notion of the pKa
Let the equilibrium constant be Ka =1.8x10^(-5). Then by definition pKa=-log(Ka) , log in base 10
pKa = - log(1.8x 10^(-5))
First set [MODE] to [COMP] by pressing [MODE] 1.
[LOG] [(] 1.8 [x] [SHIFT] [10 to the x] [(-)] 5 [)] . [(-)]
The [(-)] key is the change sign key : a small - between parentheses. The last [(-)] sign in the expression takes the negative of the whole calculation to obtain the correct value of the pKa.
The value you should find for the above exemple is 4.74
Hope it helps.
Posted on Sep 18, 2009
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Posted on Jan 02, 2017
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