PHYSICAL AND CHEMICAL CHANGE

The change does not actually make any new substance, we say it is a physical change. Most physical changes are quite easy to reverse. Some reactions are fast and some are slow.

PHYSICAL CHANGE No new substance made Easily reversed

Sharing of cake

Drilling of iron

Here are more examples : Evaporation of water Melting of ice Dissolving of sugar in water Powdering the sugar Breaking of glass Tearing of paper

Chemical Changes Changes that cause to produce a new substance are called as Chemical Changes Changes which are related related with inner properties properties of substances, such as : Breaking the bonds between atoms in molecules Forming new bonds between atoms

Generally we can say that chemical changes are not not reversable but someones are reversible. For example : C + O 2  CO 2

CHEMICAL CHANGE New substance(s) made Not easily reversed

Baking of cake

Rusting of iron

Here are more examples : Burning of candle Changing of CO to CO 2 Freezing of cement Spoiling of fruit Rusting of iron Cooking of egg

Chemical changes (reactions) are shown with symbols and formulas is called chemical equation. By this way chemical reactions can be shown easily.

For example: 2Na (s) + 2H 2 O (l) → 2NaOH (aq) + ↑H 2(g) + Q(heat)

Multiple Choice Question 1 Which is true for physical change? No new substances are produced Frying of potato is a physical change Cooking of egg is a physical change New substances are produced They are not easily reversed

Multiple Choice Question 2 Which is true for chemical change? No new substances are produced Drilling of iron is a chemical change Rusting of iron is a chemical change Dividing of an apple is a chemical change Easily reversed

Multiple Choice Question 3 Which one of the following is chemical change? Dividing of apple Frying of aubergine Cutting of wood Peeling of apple