A buffer contains 0.010 mol of lactic acid (pka = 3.86) and 0.050 mol sodium lactate per liter of aqueous solution.

a. Calculate the ph of this buffer.

Question

Chemistry

Natalya Glass

19 June, 17:42

A buffer contains 0.010 mol of lactic acid (pka = 3.86) and 0.050 mol sodium lactate per liter of aqueous solution.

a. Calculate the ph of this buffer.

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Answers (1)

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Deja Choi · Answer 1

The given buffer solution contains lactic acid and sodium lactate

i. e. CH3CH (OH) COOH/CH3CH (OH) COONa

Lactic acid is therefore a monoprotic acid with pKa = 3.86

Concentration of Lactic acid = 0.010 mol/L = 0.010 M

Concentration of sodium lactate = 0.050 mol/L = 0.050 M

Based on Henderson-Hasselbalch equation, the pH of the buffer is given as:

pH = pKa + log[salt]/[acid]

pH = pKa + log [CH3CH (OH) COONa]/[CH3CH (OH) COOH]

pH = 3.86 + log[0.050/0.010] = 4.56

A buffer contains 0.010 mol of lactic acid (pka = 3.86) and 0.050 mol sodium lactate per liter of aqueous solution.a. Calculate the ph of this buffer.

A buffer contains 0.010 mol of lactic acid (pka = 3.86) and 0.050 mol sodium lactate per liter of aqueous solution.

a. Calculate the ph of this buffer.