Physical Change and Chemical Change Examples

In a physical change, substances don’t change; only their molecules are rearranged. No new substance is formed in a physical change. In Chemical Change, a chemical reaction takes place and new substances are formed. Such reaction either takes energy or releases energy.

Examples of Physical Change

• Any change in state of matter in solid, liquid or vapour and vice versa is a physical change. For example, heating water would turn it into vapour while cooling it would turn it into ice.
• Sublimation of iodine or salt; melting of gold, silver or other metals.
• Absorption of water into a towel, Crumpling a piece of paper, Pulling copper into a thin wire, cutting wood, breaking glass, ripping a paper of tin foil etc.
• Dissolving sugar in water is also an example of Physical change because sugar molecules are dispersed within the water, but the individual sugar molecules are unchanged.

Examples of Chemical Changes

• Rusting of Iron (Iron reacts with Oxygen and turns into Iron Oxide)
• Burning of all kinds of fuels results in release of energy and gases such as CO2
• Cooking of egg would denature the protein molecules; which uncoil and create cross links to become solid white.
• Fermentation in which yeast converts Carbohydrates to alcohol, CO2 and other by products.
• Souring of Milk results in production of lactic acid from lactose sugar
• Burning of Camphor
• Explosive reaction of sodium with water and phosphorous with moist air
• Setting of cement

A change is considered to be chemical reaction only if chemical bonds are broken in reactants and new bonds are formed in products. In other words, chemical reaction is a bond breaking and bond making process. In some cases, the products of a reaction recombine to form the reactants back. These are called reversible reactions. Others are irreversible reactions.

During chemical changes, there is a rearrangement of atoms that makes or breaks chemical bonds. In a chemical reaction, bonds are broken and new bonds are formed between different atoms.

Dissolving salt into water is a Physical Change or Chemical Change?

Sometimes, changes are difficult to categorize into physical or chemical changes. One definition of Physical change is that may result in re-arrangement of molecules but the molecules should not be broken apart. Although dissolving salt in water involves the breaking of chemical bonds, yet is described as physical change.

Burning of Candle is a Physical Change or Chemical Change?

Burning of candle is example of both physical and chemical change. Physical change is melting and solidifying of the wax. Chemical change is the production of heat by consuming oxygen.