Select the chemical changes from the following:
(i) Digestion of food
(ii) Boiling of water
(iii) Cooking of food
(iv) Tarnishing of silver spoon
(v) Sublimation of iodine
(vi) Electrolysis of water
(vii) Melting of butter in a pan
(viii) Burning of wood
Select the chemical changes from the following:
(i) Digestion of food
(ii) Boiling of water
(iii) Cooking of food
(iv) Tarnishing of silver spoon
(v) Sublimation of iodine
(vi) Electrolysis of water
(vii) Melting of butter in a pan
(viii) Burning of wood
- Chemical change: The changes in which new substances are formed are called chemical changes.
- In a chemical change, one or more kinds of matter are transformed into a new kind of matter.
- It is a permanent change and cannot be easily reversed.
- Physical changes are those in which the physical properties of the substances change. It is reversible and no new product is formed.
The chemical changes from the following are -
(i) Digestion of food:
- It is a chemical change because enzymes that are present in the stomach and intestines break down large macromolecules into simpler molecules so that the body can more easily absorb the food.
- Food breakdowns and forms the new substance.
(ii) Cooking of food:
It is a chemical change because after cooking the food, the raw ingredients or the vegetables cannot be regained again.
(iii) Tarnishing of silver spoon:
- Tarnishing of the silver spoon is actually the result of a chemical reaction between the silver and sulphur-containing substances in the air.
- Silver gets oxidized in the presence of oxygen in the air.
(iv) Sublimation of iodine:
- Sublimation of iodine occurs when it is heated.
- It is a chemical process because it cannot bring back to solid.
(v) Electrolysis of water:
- Electrolysis of water means the breakdown of water into hydrogen gas and oxygen gas.
- But when hydrogen and oxygen gas come in contact they don't produce water again.
(vi) Burning of wood:
- Wood changes chemically to carbon dioxide when it burns and leaves a residue of ashes.
- These ashes cannot be changed back to wood. So it is a chemical change.
The physical changes are
(vii) Boiling of water:
During boiling, water changes from liquid to a gaseous state, and on cooling the gaseous state or vapours can be converted back to the water. So a new product is formed.
(viii) Melting of butter in a pan:
Melting of butter only changes the shape of butter from solid to liquid. On cooling, it can return to its original shape
- Chemical change: The changes in which new substances are formed are called chemical changes.
- In a chemical change, one or more kinds of matter are transformed into a new kind of matter.
- It is a permanent change and cannot be easily reversed.
- Physical changes are those in which the physical properties of the substances change. It is reversible and no new product is formed.
The chemical changes from the following are -
(i) Digestion of food:
- It is a chemical change because enzymes that are present in the stomach and intestines break down large macromolecules into simpler molecules so that the body can more easily absorb the food.
- Food breakdowns and forms the new substance.
(ii) Cooking of food:
It is a chemical change because after cooking the food, the raw ingredients or the vegetables cannot be regained again.
(iii) Tarnishing of silver spoon:
- Tarnishing of the silver spoon is actually the result of a chemical reaction between the silver and sulphur-containing substances in the air.
- Silver gets oxidized in the presence of oxygen in the air.
(iv) Sublimation of iodine:
- Sublimation of iodine occurs when it is heated.
- It is a chemical process because it cannot bring back to solid.
(v) Electrolysis of water:
- Electrolysis of water means the breakdown of water into hydrogen gas and oxygen gas.
- But when hydrogen and oxygen gas come in contact they don't produce water again.
(vi) Burning of wood:
- Wood changes chemically to carbon dioxide when it burns and leaves a residue of ashes.
- These ashes cannot be changed back to wood. So it is a chemical change.
The physical changes are
(vii) Boiling of water:
During boiling, water changes from liquid to a gaseous state, and on cooling the gaseous state or vapours can be converted back to the water. So a new product is formed.
(viii) Melting of butter in a pan:
Melting of butter only changes the shape of butter from solid to liquid. On cooling, it can return to its original shape
