Question

change in substance colour during a chemical reation give one example​

Answer 1

A chemical change may not always be visible to human eye but at times, it so happens that the colour of chemicals changes after undergoing a chemical change. When two or more substances combine to react, they produce a different structure, which has a total different composition and color.

 Example:

 Reaction of iron and copper sulphate

 CuSO4+Fe=FeSO4+Cu

 Color changes from blue to light green.

OR

Copper reacts with oxygen, H2O and CO2 to give copper carbonate, which changes color from brown to blue or blue green.

Rusting, blackening of surfaces of cut vegetables and fruits are other examples of change of color in a chemical reaction.