The document summarizes the different states of sulfur - solid, liquid, and plastic solid - and the chemical bonds involved in the phase changes.
1) Solid sulfur consists of S8 molecules held together by weak van der Waals forces, which break at 112°C to form a liquid.
2) Heating the liquid to 200°C breaks the stronger covalent bonds, forming long polymer chains that further react to form a viscous substance.
3) Breaking the polymer chains into shorter segments by heating to 444°C produces a runny liquid.
4) Cooling this liquid by adding it to water forms a plastic solid as the shorter chains slow down.
1. The Structure and Bonding of Plastic Sulphur …It’s like the bond between people…
2. Yellow solid On the left, Sulphur is in a yellow solid crystal state which consists of S8 molecules that are held together by Van der Waal’s (a weakforce that exists between each molecule). Tip: Imagine that in the image on the right, each person represent 2 Sulphur atoms which bond together to form a S8molecule. –And the jigsaw platform between the circle of people is the “not so strong” force that unites all the molecules together, making it a solid substance since they’re unable to move.
3. Yellow Solid + Heat Here, the yellow solid is heated at 112°C over a Bunsen burner and eventually turns into a yellow liquid state. In this case the Van der Waal’s are broken easily at a low temperature due to being a weak force, allowing S8 molecules to move freely and therefore a yellow liquid is formed.
4. Yellow Liquid + Heat When the yellow liquid is over the Bunsen burner at 200°C, it forms into a reddish/brown viscous (very thick and non-runny) state. Here, a high temperature is needed to break the Covalent bonds (the very strong force that holds the atoms in a molecule together) and make chains of Sulphur molecules which then polymerise to form one long chain. Tip: Imagine 8 people in a circle (8 atoms in a S8 molecule) holding hands. The bond made by their hands represent the covalent bonds between each atom. Due to a bit of heat, two people break their original bond and form another one with somebody else until everybody is joined into a long chain.
5. Reddish/Brown Viscous substance + Heat When the viscous substance is placed over the Bunsen burner at 444°C, it then forms into a red runny liquid state. Here, the long polymerised chain of S8 molecules are broken into shorter chains as once again the high temperature makes some of the strong covalent bonds to break. This creates more room for the shorter chains to move freely and therefore a runny liquid is formed. Tip: Imagine a long extended chain of people holding hands. It is harder to move when there are too many people bonded together, but smaller numbers of people in a chain enables them to move about quicker.
6. Red Runny Liquid + Water Last, the red runny liquid is poured into a beaker of water. This cools the substance and therefore slowing down the shorter chain’s movements, basically forming the substance into a stretchy/plastic solid state.
