Practice question · Estimate
A buffer is made from an acid of with a conjugate base to acid ratio of 10 to 1. Set the pH of this buffer.
Estimate on a scale from pH 3 (3) to pH 8 (8).
Hints
- Add the logarithm of the ratio to the pKa.
- The log of 10 is 1, so the pH sits one unit above the pKa.
Show the answer
5.75 (answers within ±0.2 count)
Why
. A tenfold excess of conjugate base buys exactly one pH unit, and pushing much beyond that leaves the buffer with very little capacity against added base.
Practise Buffers, Hydrolysis and Titration
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