Matter Around Us

Matter Around Us

Introduction

The term "matter" has different meanings for scientists and common people. In science, matter refers to anything that occupies space and has mass. Examples include metals, non-metals, synthetic and natural fibers, acids, bases, water, food, clothes, air, and our bodies.

States of Matter

Matter exists in three states: solid, liquid, and gas. Water can exist in all three states as ice (solid), liquid water, and water vapor (gas).

Examples of States of Matter

Wood and coal are solids, while petrol and milk are liquids. Although milk and petrol are both liquids, they have different properties.

Properties of Solids, Liquids, and Gases

Shape and Volume

• Solids: Have a definite shape and fixed volume. They remain rigid with distinct boundaries when dropped on the floor.
• Liquids: Take the shape of their container but maintain a fixed volume. Liquids can flow easily and are also called fluids.
• Gases: Have neither a fixed shape nor a fixed volume. Examples include CNG (Compressed Natural Gas).

Compressibility

Gases are highly compressible compared to liquids and solids. This property is utilized to store large volumes of gas in small cylinders, like LPG (Liquefied Petroleum Gas) and CNG.

Special Cases

• Rubber band: Changes shape when stretched but returns to its original shape when the stretching stops. It is a solid.
• Powdered salt: Takes the shape of the container but is not a liquid; it consists of individual solid particles.
• Sponge: Can be compressed, but it is a solid because it regains its shape when the compression stops. Air is expelled during compression.

Diffusion

Diffusion of Gases (Activity-4)

Diffusion is the movement of particles from one place to another. When an incense stick is lit, the scent in vapor form and smoke mix with air and spread throughout the room.

Diffusion of Liquids (Activity-5)

Liquids also diffuse into each other, similar to gases. For example, ink or potassium permanganate solution spreads evenly throughout water.

Diffusion of Solids into Liquids (Activity-6)

Solids can diffuse into liquids. For example, crystals of potassium permanganate or copper sulfate diffuse in water.

The rate of diffusion varies among solids, liquids, and gases. Gases diffuse faster than liquids, and liquids diffuse faster than solids.

Importance of Diffusion

Diffusion is vital for living things. Oxygen and carbon dioxide diffuse and dissolve in water, supporting aquatic life. During respiration, oxygen diffuses from the lungs into the blood, and carbon dioxide diffuses from the blood into the lungs.

Lab Activity: Diffusion of Two Gases

Ammonia and hydrochloric acid gases react to form white fumes of ammonium chloride. The speed of diffusion can be observed by noting how fast the white ring appears in a glass tube.

NH3(g) + HCl(g) \rightarrow NH4Cl(s)

Distinguishing Between Solids, Liquids, and Gases

Change of State

Matter can change its state. For example, coconut oil becomes solid on cooling, and camphor changes directly from solid to gas (sublimation).

Sublimation

Sublimation is the process where a substance changes directly from a solid state to a gaseous state without passing through the liquid state.

What is Matter Made Of?

All matter is made of tiny particles. To understand matter, it is essential to know the details about these particles and their arrangement.

Activity-7: How Small are the Particles of Matter?

Dissolving a few crystals of potassium permanganate in water and then diluting the solution repeatedly shows that even a small crystal contains many tiny particles that uniformly distribute in water.

Activity-8: Space Between Particles

Adding salt to water and stirring it thoroughly does not significantly change the water level, indicating that liquid particles have space between them, and solid particles occupy this space upon dissolving.

Particles of Matter Attract Each Other (Activity-9)

Particles of matter have forces of attraction between them that keep the particles together. This force varies in strength in different forms of matter.

How Diffusion Takes Place

Diffusion occurs because particles of matter move continuously. In gases, the particles move at high speed and have large spaces between them, resulting in faster diffusion.

The arrangement of particles in solids, liquids, and gases affects the rate of diffusion.

• Solids: Particles are closely packed.
• Liquids: Particles move freely and have greater space between them.
• Gases: Particles have large gaps between them.

Diffusion is faster in a vacuum because there are no particles to obstruct the movement.