Matter and its Properties - SS1 Chemistry Past Questions and Answers - page 3

Physical and chemical properties are two distinct categories used to describe and characterise matter. Understanding the difference between these properties is essential in the study of materials and their behaviour.

 

Physical properties of matter are characteristics that can be observed or measured without changing the substance's chemical composition. These properties provide information about how a substance behaves under certain conditions. Examples of physical properties include:

 

Colour: The visual appearance of a substance, such as red, blue, or transparent.

Density: The mass per unit volume of a substance.

Melting point: The temperature at which a solid substance changes to a liquid state.

Boiling point: The temperature at which a liquid substance changes to a gaseous state.

Solubility: The ability of a substance to dissolve in a particular solvent.

Conductivity: The ability of a substance to conduct heat or electricity.

Odour: The characteristic smell associated with a substance.

Hardness: The resistance of a substance to being scratched or dented.

 

These physical properties help identify and classify substances, and they can often be measured or observed using various experimental techniques.

 

On the other hand, chemical properties of matter describe how a substance interacts with other substances and undergoes chemical changes. These properties involve the transformation of matter into new substances with different chemical compositions. Examples of chemical properties include:

 

Reactivity: The ability of a substance to undergo chemical reactions with other substances.

Combustibility: The tendency of a substance to burn or react with oxygen to produce heat and light.

Stability: The ability of a substance to resist chemical changes or decomposition.

Oxidation: The reaction of a substance with oxygen, resulting in the formation of oxides.

pH: The measure of acidity or alkalinity of a substance.

Corrosion: The gradual destruction or deterioration of a substance by chemical reaction, often with oxygen or moisture.

 

Chemical properties are crucial for understanding how substances interact and transform in chemical reactions. They are often determined through laboratory experiments and observations.

In summary, physical properties of matter can be observed or measured without changing the substance's chemical composition, while chemical properties describe the behaviour of a substance in chemical reactions and its ability to undergo changes in composition. Both types of properties play a significant role in characterising and understanding the behaviour of matter.

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.