Q5(b). Acetic acid-NaOH titration curve
100 mL of 0.1 M acetic acid (Ka = 1.82 × 10⁻⁵) is neutralised with 0.1 M sodium hydroxide solution at 25 °C. Calculate the pH at (i) the initial point; (ii) when 50 mL of alkali has been added; (iii) at the equivalence point, and also (iv) when 100.1 mL of alkali has been added. Show the titration curve. Suggest a suitable indicator. [Given: Ionic product of water (Kw) at 25 °C = 1.1 × 10⁻¹⁴]
Model answer
The free solution for 2023 answers questions 1, 3, 4, 7, 8 and 10, the ones picked in its time plan. Question 5 is answered in full in the Geo-Scientist Chemistry Paper I, 2021 to 2025 book, with every part of every paper.
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UPSC Combined Geo-Scientist (Main) Chemistry Paper I: Model Answers 2021 to 2025
- All eleven questions of each paper, with the question printed above its answer
- Titration, gravimetric and nuclear numericals worked with units; structures drawn
- Topic-wise weightage and a topic-wise index
Coversweak acid strong base titrationacetic acid NaOHtitration curveHenderson equationindicator selection
All parts of Question 5
- 5(a) Two-stage titration of sodium carbonate15 marks
- 5(b) Acetic acid-NaOH titration curve15 marks