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#### zoh899

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##### Buffer solution calculation help please
« on: October 12, 2020, 09:04:15 AM »
A buffer solution is to be made using 1.00 mol dm–3 ethanoic acid, CH3CO2H, and
1.00 mol dm–3 sodium ethanoate, CH3CO2Na.
Calculate to the nearest 1 cm3 the volumes of each solution that would be required to
make 100 cm3 of a buffer solution with pH 5.50.
Clearly show all steps in your working.

Ka (CH3CO2H) = 1.79 × 10–5 mol dm–3

Ok so I used the equation pH=pka+log([base]/[acid])
I got [base]/[acid]=5.66, but I have no idea how to proceed further, since I don't know the number of moles of the ethanoic acid or of sodium ethanoate, however in the answer key they have simply put it like this
B+A=100, B=100-A (B=base, A=acid)
(100-A)/A=5.66 and they got the volume of acid as 15cm^3 and of base 85cm^3.

#### Babcock_Hall

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##### Re: Buffer solution calculation help please
« Reply #1 on: October 12, 2020, 10:02:42 AM »
You know the volume of the buffer and other critical pieces of information.

#### zoh899

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##### Re: Buffer solution calculation help please
« Reply #2 on: October 12, 2020, 11:26:55 AM »
You know the volume of the buffer and other critical pieces of information.
but there are no number of moles given and conc formula is n/v, the original volume is not given so how do I calculate the moles?

#### Borek

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##### Re: Buffer solution calculation help please
« Reply #3 on: October 12, 2020, 01:25:30 PM »
A an B are volumes, aren't they?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

#### zoh899

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##### Re: Buffer solution calculation help please
« Reply #4 on: October 12, 2020, 02:15:29 PM »
A an B are volumes, aren't they?
arent they concentrations of the respective base and acid???

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