Indian Forest Service (Mains), Chemistry optional · 2022 · Paper I

Q3(c). Sulfur phase diagram and metastability

15 marks
Topic: Phase equilibria and solutions
Question only

Question

Draw the phase diagram of the sulphur system and indicate the existence of the following metastable equilibria: S_R ⇌ S_V and S_L ⇌ S_V. Explain the reasons behind these equilibria.

Model answer

The free solution for 2022 answers questions 1, 2, 4, 5 and 6, the ones picked in its time plan. Question 3 is answered in full in the IFoS Chemistry Paper I, 2021 to 2025 book, with every part of every paper.

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UPSC Indian Forest Service (Main) Chemistry Paper I: Model Answers 2021 to 2025

All eight questions of each paper, with the question printed above its answer
Physical chemistry numericals worked with units; inorganic structures drawn
Topic-wise weightage and a topic-wise index

Printed copy Kindle edition Read sample pages

Topic notes: the phase rule, phase diagrams, the Clausius–Clapeyron equation, eutectics and partially miscible liquids, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coverssulphur phase diagrammetastable equilibriumrhombic and monoclinic sulphurphase ruletriple point

All parts of Question 3

3(a) Molecular orbitals of linear BeH₂10 marks
3(b)(i) Adiabatic mixing of ice and hot water10 marks
3(b)(ii) Trouton rule5 marks
3(c) Sulfur phase diagram and metastability15 marks