Question

Heating of sugar is a ___________ change.

Answer 1

Hint: Matter can either change physically or chemically. In physical change, only the appearance of a substance changes, its chemical composition remains the same. In chemical change, a substance changes into an entirely new substance which has a new chemical composition.

Complete answer:
Heating of sugar is a physical change.
Sugar starts melting at around \[140^\circ C\] and after that starts to decompose into a brown substance. This browning of sugar is also called caramelisation. The taste of sugar starts changing from being sweet to a bitter flavour. If further heated, it starts to turn black and gives off fumes as the sugar decomposes down to carbon, while hydrogen and oxygen evaporates as organic fragments. At this point the change becomes chemical.

Additional information:
The process of caramelization is temperature-dependent. Specific sugars have their own point at which the reactions begin to proceed readily. Impurities in the sugar, such as the molasses remaining in brown sugar, greatly speed the reactions. It is a type of non-enzymatic browning reaction. As the process occurs, volatile chemicals are released producing the characteristic caramel flavour.

Note:
Be careful if you are performing this experiment as melted sugar is very hot and is very adhesive. It can cause very severe burns if it falls on skin. Also, if sugar is heated very quickly, it will ignite to form carbon dioxide and water vapour.