# Seeming discrepancy between pKa and corresponding Ka of methylamine

The first entry in PubChem for the $$\mathrm pK_\mathrm a$$ of methylamine is $$10.657$$ at $$25\ \mathrm{^\circ C}$$. My elementary understanding is that this would be found as the negative log of the $$K_\mathrm a,$$ but the $$K_\mathrm a$$ is given as $$2.70\times10^{-11}$$ for which the negative log is about $$10.568$$.

My guess was that the two are determined independently, but can anyone shed some light on the seeming discrepancy?

• A discrepancy of 0.1 in pKa is as good as no discrepancy at all. – Ivan Neretin Oct 5 '18 at 11:34
• @IvanNeretin: Oh. They are each found experimentally...? – daniel Oct 5 '18 at 11:55
• Maybe.$\mathstrut$ – Ivan Neretin Oct 5 '18 at 11:57
• Humans create all that data. I'd guess that the 5 and 6 got transposed. – MaxW Oct 5 '18 at 13:30