Boiling sugar is a physical change. Let me explain…
Table sugar (sucrose) is a disaccharide made up of two monomers, glucose, and fructose. When heated, sugar first melts and changes from a solid to a liquid state. With further heating, sucrose breaks down into glucose and fructose. With even more heat, water is lost.
The individual components of glucose and fructose react with each other to produce several different compounds. These different compounds provide different flavor elements for caramel, such as nutty, butterscotch, and toasty flavors. With an increase in temperature, the color of sugars darkens. This process is known as caramelization.
Heating sugar at a very high temperature for a long time turns it into a black powdery substance called charred sugar. This is a chemical change.
Sucrose is a carbohydrate (hydrate of carbon). Its chemical formula is C12H22O11. When heated, it decomposes into carbon and water.
The water is lost as steam, leaving only black ashes that contain carbon.
Caramelisation is the browning of sugar. It’s widely used in cooking to obtain a brown color and sweet, nutty flavor.
ALSO SEE: Is Sugar Melting A Chemical Change or Physical Change?
Is Boiling Sugar to Make Caramel Physical Or Chemical Change?
Boiling sugar is a physical change. However, burning sugar to make caramel is a chemical change.