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Acid/base question

Calculate the pH in a titration when 10cm3 of 0.1moldm-3 soltuion of NaOH has been added to the 10cm3 of a 0.25moldm-3 solution of ethanoic acid (ka=1.76x10^5)

thanks.

First i found moles of NaOH
Then moles of ethanoic acid

stuck on why the moles of NaOH = moles of conjugate base of ethanoic acid.

(edited 10 years ago)

Reply 1

Borek

Original post by Zenarthra

stuck on why the moles of NaOH = moles of conjugate base of ethanoic acid.

Because of the neutralization reaction stoichiometry.

If you want to be very precise, amount of CH₃COO^- is slightly different from the amount of NaOH added, as after neutralization new dissociation equilibrium between CH₃COO^- and CH₃COOH is established. But the difference is negligible.