Gce Model Questions Vol1 2017 Chemistry Question 7

Practice essay / theory question 7 from the 2017 Gce Model Questions Vol1 Chemistry examination. This question covers Acids, Bases, Salts, Buffer solutions, Henderson–Hasselbalch equation .

Gce Model Questions Vol1 2017 Chemistry Essay / Theory

Topics: Acids Bases Salts Buffer solutions Henderson–Hasselbalch equation

Question 7 GCE_MODEL_QUESTIONS_VOL1 • 2017 • CHEMISTRY • essay

A buffer solution is prepared by dissolving 0.20 mol of acetic acid (CH₃COOH) and 0.30 mol of sodium acetate (CH₃COONa) in enough water to make 1.00 L of solution. The acid dissociation constant of acetic acid at 25 °C is Ka = 1.8 × 10⁻⁵. Answer the following:

Question Parts

( a )

Calculate the pH of the buffer solution before any other substance is added. Show all steps.

( b )

0.050 mol of a strong acid (HCl) is added to the buffer (assume the total volume remains 1.00 L). Calculate the new pH of the solution after the acid has reacted completely with the acetate ion. Show your reasoning.

( c )

Explain, in the context of the calculations above, why the buffer resists a large change in pH and state the practical limitation of its buffering capacity.

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About This Question

This is Gce Model Questions Vol1 2017 Chemistry Question 7. It is one of the essay questions from the 2017 Gce Model Questions Vol1 Chemistry examination.

The question covers Acids, Bases, Salts, Buffer solutions, Henderson–Hasselbalch equation .

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