Physical n Chemical Changes
Transcript of Physical n Chemical Changes
CHAPTER 5: ENERGY AND CHEMICAL CHANGES
5.1 Physical and chemical changes
Introduction Living thing Non-living thing
I. Both living and non-living thing are matterII. Matter around us undergoes changes. These
changes can be classified into two types - physical changes - chemical changes
Physical changes
1. Physical changes in a substance is one that effect its physical properties, such as
• Shape
• Volume
• Density
• State of matter (solid,liquid,gas)
• Colour
• Mass
Physical changes
2. No new substance is form during a physical change.
3. Physical changes are usually reversible. This mean that the physical properties of the substance which has undergone a physical change can be changed back.
Water ice water
Physical changes 4. Examples
a) Changes of physical state
• Caused by heating
Steam water ice
Ice water steam
• Caused by cooling
• No new substance form because H2O remain H2O
Physical changes b) Dissolving a solid in water
Sugar + water aqueous sugar ( larutan gula)
• Reverse changes
Aqueous sugar sugar + water evaporated
dissolved
Aqueous sugar sugar + water distillation
Physical changes c) Crystallizing a salt from it saturated solution
• Saturated salt means a solution with
maximum quantity of the salt dissolved on
it.
• Solid salt can be obtained by crystalization
1. Changes of matter that produce new substance2. The new substance have chemical properties
which are different from the original substance 3. Chemical changes are usually difficult to
reverse. This means that the product formed cannot be easily changed back into the reactant
Chemical Changes
Chemical Changes
a) Burning of paper
4. Example
Paper ash + carbon dioxide Burn
but
Ash + carbon dioxide Cannot be
paper
Chemical Changesb) Browning of a peeled apple
Peeled apple browning appleExposed to air
Chemical Changesc) Combustion of feul
Hydrocarbon + oxygen carbon dioxide + oxygen
Chemical Changesd) Photosyntesis
Carbon dioxide + water glucose + oxygenlight
(in plant)
Examples in daily life Physical changes in daily life
Chemical changes in daily life
Freezing of water to form ice cube
Boiling an egg to get a hard-boiled egg
Boiling of water Burning of fossil fuel in motor vehicles
Dissolving sugar or salt in water
Respiration in living organism
Melting of wax to form different shapes of candles
Decomposition of fallen leaves
Melting of chocolate Digestion of food in our body
Evaporate of sweat Photosynthesis in green plants
No Formation of new substance
Yes
reversible Reversibility Difficult to reverse
Less energy is needed
Amount of energy required
More energy is needed
Changes in physical properties only
Change in properties
Changes in chemical and physical properties
Comparison between physical and chemical changes
Physical changes Chemical changes
SIMILARITIES
Substance in both processes undergo changes
Both changes require energy
DIFFERENCESIn term of
No Formation of new substance
Yes
reversible Reversibility Difficult to reverse
Less energy is needed
Amount of energy required
More energy is needed
Changes in physical properties only
Change in properties
Changes in chemical and physical properties
Comparison between physical and chemical changes
Physical changes Chemical changes
SIMILARITIES
Substance in both processes undergo changes
Both changes require energy
DIFFERENCESIn term of