Neco 2017 Chemistry Question 7

Practice essay / theory question 7 from the 2017 Neco Chemistry examination. This question covers Acids Bases and Salts .

Neco 2017 Chemistry Essay / Theory
Topic: Acids Bases and Salts
Question 7 NECO • 2017 • CHEMISTRY • essay

A 0.250 mol sample of a weak diprotic acid H2A (Ka1 = 1.2×10^-4, Ka2 = 4.0×10^-9) is dissolved in 1.00 L of water at 25 °C.

Question Parts

( a )
Write the step‑wise dissociation equations for H2A and state which dissociation is predominant in aqueous solution. Give a brief explanation.
( b )
Assuming only the first dissociation contributes significantly, calculate the pH of the solution.
( c )
A 25.0 mL aliquot of the above solution is titrated with 0.100 M NaOH. (i) Determine the volume of NaOH required to reach the first equivalence point. (ii) Calculate the pH at the first equivalence point.
( d )
After the addition of 0.050 L of 0.100 M NaOH to the 25.0 mL aliquot (i.e., 5.0×10^-3 mol OH⁻, which is beyond the first equivalence point), identify the predominant ionic species present and calculate the pH of the solution at this stage.

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About This Question

This is Neco 2017 Chemistry Question 7. It is one of the essay questions from the 2017 Neco Chemistry examination.

The question covers Acids Bases and Salts .

View More Neco 2017 Chemistry Questions More Neco Practice Questions Back to Questions

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