Q5(a). Two-stage titration of sodium carbonate
50 mL of 0.1 N sodium carbonate is titrated with 0.1 N HCl at 298 K. Explain the course of titration with necessary equations. Calculate the pH values at the equivalence points. Suggest appropriate indicators. [Given: K₁ for H₂CO₃ = 4.3 × 10⁻⁷ and K₂ for H₂CO₃ = 5.6 × 10⁻¹¹]
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
Coverssodium carbonate titrationHCl vs Na2CO3two equivalence pointsphenolphthalein and methyl orangepolyprotic acid titration
All parts of Question 5
- 5(a) Two-stage titration of sodium carbonate15 marks
- 5(b) Acetic acid-NaOH titration curve15 marks