The viscosity of liquid sulfur increases sharply at about 160 °C and then decreases again above 200 °C. Explain.

Verified step by step guidance

1. Step 1: Understand the concept of viscosity, which is a measure of a fluid's resistance to flow. In general, higher viscosity means a thicker fluid that flows less easily.
2. Step 2: Recognize that sulfur exists in different allotropes, which are different structural forms of the same element. At different temperatures, sulfur can change its structure, affecting its physical properties like viscosity.
3. Step 3: At around 160 °C, sulfur undergoes a transformation from S8 rings to long polymeric chains. This structural change increases the viscosity because the long chains can entangle, making the liquid more resistant to flow.
4. Step 4: As the temperature increases further above 200 °C, the polymeric chains begin to break down into smaller fragments. This breakdown reduces the entanglement and thus decreases the viscosity.
5. Step 5: Conclude that the sharp increase in viscosity at 160 °C is due to the formation of long polymeric chains, and the decrease above 200 °C is due to the breakdown of these chains into smaller units.