Acetic acid (CH3COOH, abbrev HA) is a very common weak acid with pKa = 4.75 (at 25oC and low ionic strength) A] Write down the dissociation equation of the weak acid HA in aqueous solution, derive the respective formulae for the dissociation constant Ka and pKa. B] Calculate pH of the diluted solution of acetic acid with concentration, c = 0.05 mol/dm3 C] What is the approximate pH of the aqueous acetate buffer solution composed of dissolved mixture of acetic acid (HA) and sodium acetate (NaA) in the same respective concentrations? What is the working pH range of acetate buffers?
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Acetic acid (CH3COOH, abbrev HA) is a very common weak acid with pKa = 4.75 (at 25oC and low ionic strength)
A] Write down the dissociation equation of the weak acid HA in aqueous solution, derive the respective formulae for the dissociation constant Ka and pKa.
B] Calculate pH of the diluted solution of acetic acid with concentration, c = 0.05 mol/dm3
C] What is the approximate pH of the aqueous acetate buffer solution composed of dissolved mixture of acetic acid (HA) and sodium acetate (NaA) in the same respective concentrations? What is the working pH range of acetate buffers?
D] How can you prepare exactly 1 dm3 of acetate buffer solution with required pH 5.0 and the total concentration [HA + NaA], c = 0.01 mol/dm3 if the stock solution of acetic acid (HA) with concentration,
cHA = 0.1 mol/dm3, anhydrous sodium acetate (NaA, MT = 82.03 g/mol) and purified water are available?
E] Acetate buffer solution may be also prepared by the partial neutralization of HA with NaOH: 20 cm3 of the solution of NaOH, 0.1 mol/dm3 were mixed with 50 cm3 of the solution of HA with the same concentration, and water added up to 100 cm3. Calculate the respective equilibrium concentrations [HA], [A] and pH of the final buffer solution.
F] Write down the equation of hydrolysis of sodium acetate in aqueous solution and calculate pH of the solution of NaA 0.01 mol/dm (pKw = 14.00)
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