The high viscosity of sulphur is due to the ring type structure or polymerization of sulphur. Also in liquid sulphur, H2S is the reason which affects its viscosity significantly.
To get the viscosity of liquid sulphur closer to pure sulphur, It is necessary to get it degassed in a sulphur tank based on its source. The H2S tends to make the liquid sulphur less viscous. It can be understand well by quenching the sealed capsules. For some days, the polymer rubbery state of sulphur persists and finally decomposes into the sulphur powder.
The equipment required for the demonstration-
Powdered sulphur [note: Don't use sublimated sulphur. Also grinding solid sulphur are annoying due to charging during the crushing]
Large test tube
Appropriate holder for tube
Fisher burner and striker
500mL or bigger beaker filled with 300-400 mL of water.
At first, put about 2 inches sulphur into the test tube. Heat the tube slowly. Tip tube to show the viscosity of melted sulphur and continue to heat. Viscosity drops with the increasing heat of liquid. Keep showing the viscosity of sulphur while continue heating the tube over burner. There will be some points where sulphur would become molasses. Viscosity starts dropping as heat is applied to it. This change in viscosity can be seen by cooling the tube and molasses reappear. After reheating the sulphur above its viscosity state, pour it into the water in beaker. It will solidify into rubbery material and become plastic sulphur, yellow, rhombic form.
Following are the different stats it passes-
In starting, sulphur has S8 rings structure and crown shape.
On heating sulphur get melted. With increase in heat, bond between rings become strained and eventually broken. A diradical is formed by equally breaking of covalent bonds.
TThen, polymerization process takes place. In this, two radicals come closer to each other in order to form a long chain. By adding to radicals on other molecules there's a long chain formed.
When the polymers are formed, viscosity increased.
Regular heating the polymers, kinetic energy once again stretches & breaks the bonds, which results in a liquid containing small fragments of sulphur chains. At this point viscosity is lower and can be felt by the ease motion of polymeric sulphur. When sulphur is boiled it contains S8, S4 fragments.