Question

how is a chemical change different from a physical change​

Answer 1

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How is a chemical change different from a physical change ?

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$\mathbb{PHYSICAL \: CHANGE}$

✪ A change in which no new substance is formed , only physical appearnce is changed .

✪ It is a reversible change.

✪ It is a permanent change .

✪ It does not produce energy during the process .

✪ Example : Boiling of water , melting if ice etc.

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$\mathbb{CHEMICAL \: CHANGE}$

✪A change in which one or more substance formed a new substance.

✪It is non reversible change.

✪It is a permanent change .

✪It produces energy during the process in terms of heat , light and sound.

✪ Example : Burning of coal , Rusting of iron etc.

Answer 2

Answer:

• Chemical change:- A chemical change has following characteristics:

1. A chemical change is only possible, when the absorption of energy or evolution of energy takes place.
2. During the chemical change the chemical properties or chemical composition of substance change.
3. In a chemical change, there is a formation of new substance.
4. Chemical change is a permanent change.
5. The original substance or reactant cannot recovered once chemical change happened. Because, it is irreversible in nature. Foe example: rusting, burning of coal etc.

• Physical change:-  A physical change has following characteristics

1. In the physical change very small amount of energy or no energy is usually absorbed or evolved in form of light or sound.
2. Physical properties such as volume , odour, density  or color etc. will change while no change in the chemical properties.
3. There is no new compound is formed.
4. Physical change is a temporary change.
5. Physical change is reversible in nature. The reactants can be regenerated by simple physical method. For example:  melting of wax, freezing of water etc.