When sulphur is heated, then first a red liquid is obtained, which is quite mobile. If heating becomes stronger, then the liquid becomes more and more
viscous until it become a slowly moving thick syrup. This is due to breakup of the S8-rings and catenation of the strings of sulphur atoms into large
strings. When heating further continues, then the strings of sulphur break up in shorter strings and the liquid becomes more mobile again.
When sulphur is heated to a temperature well beyond its maximum of viscosity, then it becomes more easy to ignite. It burns with a very small blue
flame and gives off mostly SO2 and a little SO3. You can actually see the little amount of SO3 formed. The burning liquid sulphur gives off a faint
smoke, hardly visible, but when sunlight shines on it, one can clearly see it. |