# Chemistry Kb question need to clarify something

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the pKb for methylamine is 3.36, what is the Kb for methylamine?

pKa+pKb= 14.00

Kb= 10^-pKb = 4.4x10^-4 is the answer

but HOW?? what is punched into the calculator to get 4.4 x 10^-4??

• Chemistry Kb question need to clarify something -

pKb = 3.36
pKb = -log Kb
3.36 = -logKb
-3.36 = log Kb
Punch in 3.36 and hit the change sign button OR punch in -3.36 directly, then hit the 10^x key. That will return 4.36515E-4 which rounds to 4.36E-4.

• Chemistry Kb question need to clarify something -

-3.36(log button or 10^x button)= syntax error ??

• Chemistry Kb question need to clarify something -

the key sequence will depend on the type of calculator that you have. If it is a VPAM or similar (like a Casio FX-83) then the sequence is something like

<shift><10^><-><3><.><3><6><=>

and the display will show

0.0004365

(depending on how the display is set up).

The exact key sequence will depend on the model of calculator you have.