Chemical Change and Physical Change
Here we will learn about chemical & physical change, examples of physical & chemical changes of matter, chemical reaction and its types etc.
Chemical and physical change occur all around you in everyday life. But how can you tell if a substance has undergone a chemical or a physical change, and what is the difference? So it is very important to understand the concept of chemical and physical changes.
What is a Chemical Change of Matter
A chemical change is the process in which one kind of substance is changed into a different kind of substance. Chemical changes produce substances that were not there when it was started. It means the changes in chemical change are irreversible and permanent.
Chemical Change Examples
- Iron rusting
- Burning firewood
- Organic matter
- Fruit ripening
- Digesting food
- Frying an egg
- Spoiled food
- Teeth decaying
- Respiration (breathing)
- Fireworks exploding
- Souring of milk
Some More Examples of Chemical Changes
Signs of Chemical Changes
Following are the possible signs of chemical change:
- Change in Temperature
- Change in Color
- Change in odor
- Change in taste
- Formation of a Precipitate
- Formation of Bubbles
Summary - Chemical Changes
- In a chemical reaction, there is a change in the composition of the substances.
- This type of changes produce substances that were not there when it was started.
- It happen on a molecular level.
- Chemical changes produce new products.
- Chemical change is irreversible and permanent.
- It happens when atomic bonds are broken or created during chemical reactions.
What is a Physical Change of Matter
The changes in physical change are reversible and temporary. During the physical change, no new products are formed, and the molecular composition remains the same.
For example, when you melt an ice cube, it becomes liquid. Here the state is changed, but the water molecules (H2O) are still the same as ice cubes.
Physical Change Examples
- Freezing water to make ice
- Melting an ice cube
- Heating water to make steam
- A piece of of paper cut into two pieces
- Bending a paperclip
- Chopping vegetables
- Breaking a glass
- Cutting fabric
Some More Examples of Physical Change
Signs of Physical Changes
Following are the possible signs of physical change:
- Change of shape
- Change of state (solid, liquid, gas)
- Change in size
- Change in any other physical property
Summary - Physical Changes
- The physical change affects only physical properties, i.e., shape, size, weight, etc.
- In a physical change, there is no change in the composition of the substances.
- The molecular composition remains the same.
- Physical changes do not happen on a molecular level.
- Physical changes do not produce new products.
- Physical change is reversible and temporary.
What is Chemical Reaction?
A chemical reaction occurs when one or more substances change into different substances that have different physical and chemical properties. Bonds between atoms are broken and created to form new molecules.
Reactant – Reactant is the substance that goes into a chemical reaction.
Products – The substances produced at the end of the reaction are known as the products.
For example: Vinegar + Baking soda = Carbon dioxide.
Vinegar + Baking soda = Reactant
Carbon dioxide = Product
Types of Chemical Reactions
Combination Reaction – Two or more simple substances combine to form a more complex one. A combination reaction is also known as a synthesis reaction.
A + B → AB
Decomposition Reaction – The process of a complex substance being split up into simpler substances. AB → A + B
Combination and decomposition reactions are opposites.
Combustion Reaction – In this reaction, the substance reacts with oxygen gas, releasing energy in the form of light and heat. Combustion reactions must involve Oxygen as one reactant.
A+B+Oxygen = Carbon dioxide + Water
Note: Product of combustion is always water and carbon dioxide.
Frequently Asked Questions (FAQs)
Is boiling water a chemical change?
No, boiling water is not a chemical change. It is a physical change because the water vapor still has the same molecular structure as liquid water (H2O). Water boiling, melting ice, tearing paper, freezing water and crushing a can are all examples of physical changes.
Is burning a chemical change?
Yes, burning is a chemical change.
Is rusting a chemical change?
Yes, rusting is a chemical change
Is frying an egg a chemical change?
Yes, frying an egg is a chemical change because it results in the formation of new particles. The heat in the frying process gives energy to the egg's molecules and brings about a permanent change in the substance.
What are the 5 indicators of a chemical change?
These are the 5 indicators of a chemical change:
1. Change in Temperature
2. Change in Color
3. Change in odor
4. Change in taste
5. Formation of a Precipitate