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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: slutsavenue on September 30, 2013, 03:58:29 AM

Title: Buffer question PLS HELP
Post by: slutsavenue on September 30, 2013, 03:58:29 AM
A sodium acetate-acetic acid buffer solution was prepared by adding 0.020 M HCl solution to 500 ml
of 0.020 M Ch3COONa and then diluting the mixed solution to 1.0L. Calculate the original volume of the
HCl solution needed to prepare a buffer solution of pH 5.00.

The given answer is 180ml.

How do I derive the original volume of HCL solution needed to prepare the buffer solution? I used the henderson hesselberg equation in attempt to solve this answer but can't seem to get the given answer.
Title: Re: Buffer question PLS HELP
Post by: Borek on September 30, 2013, 04:19:25 AM
http://www.chembuddy.com/?left=buffers&right=composition-calculation
Title: Re: Buffer question PLS HELP
Post by: magician4 on September 30, 2013, 11:34:57 AM
the allegedly correct answer "180 mL " is WRONG

taking 4.75 as pKa for acetic acid , the correct answer would have to be 281,17 mL ~ 280 mL


regards

Ingo
Title: Re: Buffer question PLS HELP
Post by: Borek on September 30, 2013, 11:59:12 AM
the allegedly correct answer "180 mL " is WRONG

taking 4.75 as pKa for acetic acid , the correct answer would have to be 281,17 mL ~ 280 mL

180 mL is perfectly correct, please stop confusing people.