Neco Model Questions Vol1 2025 Chemistry Question 7

Practice essay / theory question 7 from the 2025 Neco Model Questions Vol1 Chemistry examination. This question covers Acids, Bases and Salts .

Neco Model Questions Vol1 2025 Chemistry Essay / Theory
Topic: Acids, Bases and Salts
Question 7 NECO_MODEL_QUESTIONS_VOL1 • 2025 • CHEMISTRY • essay

A 0.500 mol sample of a weak monoprotic acid HA (Ka = 1.2 ×10⁻⁵) is dissolved in 1.00 L of water at 25 °C. The solution is then partially neutralised by adding 0.200 mol L⁻¹ NaOH until the pH of the mixture becomes exactly 5.00.

Question Parts

( a )
Calculate the volume of the NaOH solution that must be added to attain pH 5.00.
( b )
State the concentrations of the undissociated acid HA and its conjugate base A⁻ in the buffer solution obtained after the addition of NaOH.
( c )
A small amount of strong acid (0.010 mol HCl) is added to the buffer. Calculate the new pH and comment on the buffer’s capacity to resist this addition.
( d )
Explain qualitatively how the common‑ion effect would influence the solubility of a sparingly soluble salt of the conjugate base, such as NaA, if it were added to the buffer solution prepared in part (a).

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About This Question

This is Neco Model Questions Vol1 2025 Chemistry Question 7. It is one of the essay questions from the 2025 Neco Model Questions Vol1 Chemistry examination.

The question covers Acids, Bases and Salts .

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