# AP CHEMISTRY

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What would be the pH of a solution prepared by combining equal quantities of NaH2PO4 and Na2HPO4? Explain with an equation.

• AP CHEMISTRY -

It will be pKa2.
pH = pKa2 + log[(base)/(acid)]
If base = acid, then log 1 = 0 and pH = pKa2.

• AP CHEMISTRY -

How do u find pKa2

• AP CHEMISTRY -

Look up Ka2, (and Ka1 and Ka3 will be in the same table) for H3PO4.
Then pKa2 = -log(Ka2) = ?

• AP CHEMISTRY -

ka2=6.2x10^-8
pka2=-log(ka2)=-log(6.2x10^-8)=7.2
pH=7.2

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