The document summarizes the sulphur system phase diagram. It describes that sulphur can exist in four phases: rhombic solid, monoclinic solid, liquid, and vapor. The phase diagram shows the phase boundary curves between these different sulphur phases. It includes the sublimation, vapor pressure, fusion/melting, and transition curves. The phase diagram areas represent stable regions where the sulphur can exist as rhombic solid, monoclinic solid, liquid, or vapor. Triple points occur where three phases meet in equilibrium. The diagram also shows a region of metastable equilibrium with supercooled liquid sulfur and metastable rhombic solid phases.

1. The Sulphur System Presented By Hitesh Wagle

2. The Sulphur System Sulphur can exists in four possible phases: Two solid polymorphic phases Rhombic Sulphur (S R ) (m.p. 114°C) Monoclinic Sulphur (S M ) (m.p. 120°C) Sulphur Liquid Sulphur Vapours

3. Components & Phase Rule All the four phases can be represented by the only chemical individual “SULPHUR” itself. Hence an one component system. Phase rule (F= C-P+2) becomes: F= 3-P

4. Phase Diagram of Sulphur System

5. Solid Rhombic (S R ) Liquid (L) Vapour (V) 1 atm A B C D E G F Solid Monoclinic (S M ) 95.6 Pressure (atm) Temperature °C 114 120 444.6 B.P. S R /V S M /V L/V S M /L S R /S M S R /L 1290 atm 165

6. Curves In Phase Diagram Curve AB: Sublimation Curve of Rhombic Sulphur Curve BC: Sublimation Curve of Monoclinic Sulphur Curve CD: Vapour Pressure Curve of Liquid Sulphur Curve CE: Fusion Curve of Monoclinic Sulphur Curve BE: Transition Curve Solid Sulphur Curve EG: Fusion Curve of Rhombic Sulphur At any curve, phase rule becomes, F= 3-P = 3-2 = 1 (Monovarient)

7. Curve AB: Sublimation Curve of Rhombic Sulphur

8. Curve BC: Sublimation Curve of Monoclinic Sulphur

9. Curve CD: Vapour Pressure Curve of Liquid Sulphur

10. Curve CE: Fusion Curve of Monoclinic Sulphur

11. Curve BE: Transition Curve of Solid Sulphur

12. Curve EG: Fusion Curve of Rhombic Sulphur

13. Triple Points Triple Point B Triple Point C Triple Point E At any Triple Point, phase rule becomes: F = 3-P = 3-3 = 0 (nonvarient)

14. Areas in Phase Diagram Area ABEG (Rhombic Sulphur) Area BCEB (Monoclinic Sulphur) Area DCEG (Sulphur Liquid) Area ABCD (Sulphur Vapours) In an area, Phase Rule becomes: F = 3-P= 3-1 = 2 (bivariant)

15. Metastable Equilibrium 3 Dashed curve: curve BF (sublimation curve of metastable S R ) curve CF (vapour press. Curve of supercooled liquid sulphur) curve FE (fusion curve of metastable S R ) One triple point F 3 areas: Area ABFE (Metastable S R ) Area ABFCD (Sulphur vapours) Area DCFE (supercooled liquid sulphur)

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