All of you know that, Matter has capacity to undergoing changes. This changes are of two types: Physical change and Chemical change. So, in this article we will discuss about - What is Physical change and Chemical change? And What are the difference between a Physical change and a chemical change with examples?

What is Physical change?

In simple words, physical changes are reversible. In physical change, the change in structure of matter is same before and after the change. Physical changes means changes in shape, temperature and texture of substance.

What are some examples of Physical changes?

There are many examples of physical changes :

Boiling water:

When we heated the water then is boils and changes its state from liquid state to gaseous state. But again the chemical composition of water is remains the same as before.

Salt in water:

Salt is added to water then it dissolves and forms a homogeneous mixture. Here, new substance is prepared, Hence, this is physical change.

Melting of ice :

When ice melts then it converts to liquid state from solid state. Chemical composition of water is remains the same.

Cutting a wood piece:

When we cut the wood piece then its shape changes but its chemical composition is as it is.

Tearing a paper piece:

When a paper piece is town then its chemical composition is remains same only the shape is changes.

Rubber band stretching :

When a rubber band is stretching then its chemical composition remains the same but shape of rubber band changes.

What is chemical change?

Chemical changes are irreversible. Chemical changes is occurs when composition of substance is changed, that requires the breaking and forming new chemical bonds in a chemical reaction. That means a reactant is converted to products which does not converted back to reactant.

What are 10 examples of chemical changes?

Fermentation process :

Sugar ia converted into ethanol and carbon dioxide in presence of yeast. This is chemical change.

Combustion of gasoline:

When gasoline undergoes combustion reaction in presence of oxygen then gives CO2 and H2O.

Baking soda and vinegar reaction:

When baking soda and vinegar are reacts together, then it produce CO2 gas.

Food Digestion :

Food are break down to smaller molecules in presence of enzymes present in the stomach and intestines.

Burning of a candle:

When a candle burns, then the wax is broken down into tiny molecules and produces heat, light, water vapor, and CO2.

Rusting of nails:

When nails are rusted in presence of oxygen and moisture it produces iron oxide or called as rust.

Digestion of food by enzymes:

Enzymes in the stomach and intestines chemically break down food into smaller molecules.

Rusting of metals:

When metals are undergoes to oxygen and moisture it forms metal oxide which corrodes the metal.

Rusting of iron:

When iron in presence of oxygen and moisture then it forms iron oxide rust.

Photosynthesis:

In photosynthesis process, plants use energy from the sun, CO2 , and H2O to gives oxygen and glucose.

What is the difference between a physical change and a chemical change?

• Chemical composition :

In physical change, the chemical composition is remains same only the shape, texture are changes.

In chemical change, molecular composition is changes totally. There is formation of new substance.

• Permanent or temporary change:

Physical change is temporary change.

Chemical change is permanent change.

• Energy absorption:

For physical change little amount of energy is absorbed.

In chemical change, both absorption and evolution of energy take place.

• Reaction type:

Physical change is reversible change.That is old substance or reactant can be recovered.

Chemical change is irreversible change. That means old substance or reactant cannot be recovered.

• Substance formed:.

In physical change, no new substance is formed.

In chemical change new substances are formed. It may be more than one.

What are some changes that are both physical and chemical?

There are various changes that can be both physical change and chemical changes.

Few examples of changes that are bother physical and chemical:

We know that, in digestion process, Food is broken down by chewing then it is physical change but when broken down by digestive enzymes in the saliva and acid in the stomach then it is chemical change.

Another example is when we eating chocolate, there is both a physical change because there is breaking of chocolate into smaller pieces or melting of chocolate and a chemical change is when breaking of chocolate molecules into simpler molecules.

The cycle of an internal combustion engine also contains both a physical and chemical change. For eample, when Gasoline is vaporized and the air in the container is compressed is a physical change and before being ignited and combusting then it is a chemical change.

Add water to quicklime then water turning to vapour it is a physical change. But when the H2O is combined with CaO to produce Ca(OH)2, then this is chemical reaction.

Now, take a example of rocks. They are physically changed by wind, water flow, expansion of ice as it freezes abrasive wind and water-borne sediments. But, they are chemically changed by oxygen, acid rain and acidic compounds produced by decomposers.

Burning of wood: When wood is heated then the moisture in the wood turns to vapor then it is a physical change. But, the in actual burning of wood will produces CO2 and other some products then it us chemical change.

What are some examples of chemical changes in everyday life?

Combustion : Combustion meaning burning. It is a chemical change when wood or gasoline like substances undergo burning in preseof oxygen and produces water and CO2.

Baking : It is also a chemical change occurs when the mixture of flour, sugar and eggs are heated and forms new product like cake, breads etc.

Fireworks : In fireworks, the lights and noise are generated by chemical reaction.

Battery: In battery, the chemical energy is converted to electrical energy, then it is chemical change.

Photosynthesis: In this process, plants in presence of sunlight, water and CO2 produces oxygen and sugar. Then it is also a chemical change.

How do you identify chemical and physical change?

Many times it is hard to understanding the change is physical or chemical. To detemine whether there is Physical or chemical change

Physical changes are changes in the current state of the compound. Consider, a block of ice, when first we melt the ice and converted to a cup of liquid water then it is a physical change. When water boils then the liquid water becomes a vapor which is a physical change. All you are doing is changing the state of the compound. The water never loses its identity of being water. This holds actual for any compound. The same is true for the reversal, condense the vapor into a liquid, and freeze the liquid into a solid.

Chemical changes alter the current identity of the compound. These are chemical reactions, where changes in the structure and substituents are made. Consider the hydrocarbon combustion of methane :

CH4 + 2O2 --> CO2 + 2H2O + Heat

A chemical change occurs in both of the methane and oxygen. The new products are totally different from reactants. Generally, chemical changes will have a observable change in the system. For example - Gas formation, Colour change, Precipitate formation, Exothermic means heat energy given off and endothermic means heat energy taken in production of light, and decomposition..