Plastic sulfur is formed when molten sulfur is rapidly cooled in water. It has a rubber-like structure with sulfur chains aligned parallel to one another and held together by van der Waals forces. This plastic sulfur is unstable at room temperature as the sulfur chains slowly rearrange into crystalline structures, making the material more brittle over time. Sulfur exists in different states depending on temperature, being solid below 95.6°C, liquid from 113-445°C, and transforming from low to high viscosity as it is heated through this range.

1. Plastic SulphurGreen Bay High SchoolYear 12RACHEL SONG

2. What is Plastic Sulphur ?A form of rubber-like Sulphur - produced when molten Sulphur is rapidly poured into cold water. (It is only produced with red molten Sulphur that contains S8 chains.)The S8chain Sulphur cools too rapidly to allow the chains to reform into crowns and they lose energy while parallel to one another. This creates a structure with the chains all aligned but only held by the Van der Waals’ forces.Plastic sulphur is unstable at room temperature, as the S8 chains slowly return to S8 crown molecules. The rubber-like structure gets more brittle as the crystals are slowly formed.

3. Steps of ChangeYellow solid (20ºC ~ 25ºC)Yellow liquid (113ºC)Dark & extremely viscous liquid (118 ºC)Runny liquid at boiling point (445 ºC)

4. Yellow SolidYellow S8 Solid at room temperature (20ºC ~ 25ºC)Particle:SolidForces:Van der Waals’forceProperties:powder

5. Yellow LiquidYellow S8 Liquid at melting point (113ºC)Particle: LiquidForces: Van der Waals’forceProperties:low viscosity

6. Dark brown & extremely viscous LiquidDark brown & extremely viscousS8 Liquid at 180ºCParticle: LiquidForces: Van der Waals’forceProperties:high viscosity

7. Runny Liquidat Boiling PointRunny S8 Liquid at boiling point (445ºC)Particle: LiquidForces: Van der Waals’forceProperties:medium viscosity

8. Formation of Plastic Sulphur

9. Properties of SulphurSulphur has various allotropic forms.

10. Below 95.6oC stable crystal form is rhombic.Above 95.6oC element transforms into a triclinic form. These crystalline forms both contain cyclic S8 molecules.Above melting point (113oC) molten Sulphur is a yellow liquid containing S8.

11. Sulphur Transformation

12. Properties of SulphurAt 160oC Sulphur atoms form chains, liquid becomes more viscous & dark brown. At 180oC brown & viscous Sulphur liquid.At 200oC Sulphur chains shorten.At boiling point (445oC) viscous Sulphur becomes fluid again.Into the cold water (0oC ~ 20oC) liquid Sulphur  rubber-like plastic Sulphur.