Question

(a) Discuss some characteristics of chemical changes.

(b) How is burning of wood a chemical change?

Answer 1

(a) The characteristics of chemical changes are:
1) It is a permanent change and is irreversible. ( 1 Mark)
2) New substances are formed in this change. (1 Mark)
3) Energy in the form of heat or light is either absorbed or released. (1 Mark)

(b) When wood is lit up, it burns gently and after a while, it turns into ashes. As it burns, it produces heat, light and smoke which escapes through the chimney. (1 Mark) The heat, light, fire and smoke are all good characteristics of a chemical reaction, which result in a completely new matter—ash. (1 Mark)