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Topic: Basic buffer problem!! HELP?  (Read 1665 times)

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Offline 93suzzzykim

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Basic buffer problem!! HELP?
« on: February 05, 2017, 06:25:49 PM »
Prepare 100 ml of Tris buffer (pH 8.2) by using I M HCl and 0.1M Tris Chydroxymethyl aminomethane base

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Offline AWK

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Re: Basic buffer problem!! HELP?
« Reply #1 on: February 05, 2017, 07:38:37 PM »
Find pKa (or pKb) of TRIS base. Then calculate concentration of Bronsted acid and base in Henderson-Hasselbach equation.
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Offline 93suzzzykim

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Re: Basic buffer problem!! HELP?
« Reply #2 on: February 05, 2017, 08:13:22 PM »
pH = pKa + log{[A-]/[HA]}


[HA] = TRIS-H+
[A-] = TRIS (base)

log{[A-]/[HA]} = 8.2 - 8.08 = 0.12
[A-]/[HA] = 10^0.12 = 1.318

100mL of 0.1M Tris base= 0.01 mol Molarity= moles/volume

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I'm stuck here??...
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Offline AWK

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Re: Basic buffer problem!! HELP?
« Reply #3 on: February 05, 2017, 08:44:05 PM »
Split 0.01 into two part that part1/part2=1.318.
The part corresponding to Bronsted acid is equal to number of moles of HCl.
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