Physical And Chemical Changes Flashcards
What is a physical change
Physical change is a change in which no new substance is formed
State the characteristics of physical change
. Generally, the change is temporary and reversible.
. No new substance is formed.
. The chemical composition of the original substance is not altered.
. A physical change may cause changes in state, shape, size and colour of a substance.
State 5 examples of a physical change
Breaking of a glass tumbler, sublimation, glowing of an electric bulb, dissolving salt in water,drying of clothes
How is glowing of a bulb a physical change
When an electric bulb is switched on, an electric current passes through the filament of the bulb.As a result, the filament glows to give light. However, when switched off, the filament returns to its normal condition and the bulb stops
How is subliminal a physical change?
Certain substances such as ammonium ride and camphor sublime, that is, when heated these stances directly change into gaseous state, without going through the liquid state. The vapour formed can be led to get back the solid. Thus, the change is reversible, no new substances are formed. Therefore, sublimation solid is a physical change.
What is a chemical change?
chemical change is a permanent change in which original substance loses its own composition and roperties.
Give 5 examples of chemical change.
Cooking of food, digestion of food, combination of iron and sulphur, rusting of iron respiration
State the characteristics of a chemical change
Characteristics of a chemical change
The following are the characteristics of a chemical change.
1. The change is permanent and cannot be reversed by simple physical methods.
2. One or more new substances are formed with composition and properties different from the original substances.
3. A chemical change involves an exchange of energy in the form of heat or light.
What is absorbed during a change? S
hanges involving energy
Juring a change, energy is generally evolved or absorbed 1 the form of heat, light, sound or any other form. nergy change may take place when there is a physical change. out these changes are generally smaller than the energy hanges that take place during a chemical change.
