Differentiate between physical and chemical cha... - SS1 Chemistry Matter and its Properties Question

Changes in matter can be categorised as either physical changes or chemical changes. These two types of changes have distinct characteristics and effects on the substances involved.

 

Physical changes are alterations in the physical properties of a substance that do not result in a change in its chemical composition. In other words, the substance undergoes a transformation in its appearance or state, but its fundamental chemical identity remains the same. Examples of physical changes include:

 

Change in state: The transition of a substance between solid, liquid, and gas states, such as melting ice into water or evaporating water into steam.

Change in shape or size: Alterations in the form or dimensions of a substance without changing its chemical composition, such as breaking a glass bottle or cutting a piece of paper.

Dissolving: The process of a substance dissolving in a solvent, like sugar dissolving in water. The individual particles of the substance remain the same; they are just dispersed in the solvent.

 

Chemical changes, on the other hand, involve the formation of new substances with different chemical compositions and properties. During a chemical change, the bonds between atoms are broken and new bonds are formed, resulting in a transformation at the molecular level. Examples of chemical changes include:

 

Combustion: The reaction of a substance with oxygen to produce heat, light, and new substances. For instance, burning wood or paper.

Oxidation: The reaction of a substance with oxygen, often resulting in a change in colour or the formation of rust, such as iron rusting.

Decomposition: The breakdown of a compound into simpler substances through a chemical reaction. An example is the decomposition of hydrogen peroxide into water and oxygen gas.

Digestion: The chemical breakdown of food in our bodies to extract nutrients and energy.

 

Chemical changes involve the rearrangement of atoms and the formation of new chemical bonds, leading to the creation of different substances. These changes are often irreversible and result in a complete transformation of the original material.