How do you find Ka from pH for a weak acid?

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How do you find Ka from pH for a weak acid?

2007-05-01 07:08:48 · 2 answers · asked by shreadmaster775 1 in Science & Mathematics ➔ Chemistry

2 answers

You search the pH for the half neutralisation (there is an equality of acid and salt of that acid). This pH = pKa

after this, use the formula Ka = 10^(-pKa)

2007-05-01 07:16:11 · answer #1 · answered by maussy 7 · 0⤊ 0⤋

Let the acid be called HA. You titrate with NaOH until [HA] = [Na+A-]. The pH at that point is equal to pKa

2007-05-01 07:14:57 · answer #2 · answered by steve_geo1 7 · 0⤊ 0⤋