Matter in Our Surroundings (Class 9)

What is matter?

Anything that occupies space and has mass. (anything which has mass and volume)

Early Indian philosophers classified matter in the form of 5 elements. What are they?

"Panch Tatva"-air,earth,fire,sky and water.

What are the two classifications of matter found by modern-day scientists?

1)Physical nature of matter

2)Chemical nature of matter

What are the physical natures of matter?

1)Matter is made up of particles

2)The particles are very small beyond our imagination

What are the 3 characteristics of matter?

1)Particles of matter have space between them

2)Particles of matter are continuously moving

3)Particles of matter attract each other

We have to go near to smell an unlit incense stick but we can easily smell a lit incense stick even in the corner of the room why?

This is because the particles of vapors gain more kinetic energy when it is lit and move faster in the air. This shows that the particles of matter are continuously moving.

A drop of ink poured in water takes less time to spread in water while a drop of honey takes more time to spread in water why? (clue: Density)

Density affects the state of movement of particles. Honey is denser than ink and thus takes a longer time to spread in water.

What are the 3 states of matter?

solid, liquid, and gas.

What are the properties of a solid?

It has a definite shape and volume, negligible compressibility, rigid, etc.

What are the properties of a liquid?

A liquid has a fixed volume but will assume the shape of the container it fills, hence it flows and changes shape. So they are not rigid but can be called a fluid.

What is diffusion?

The intermixing of two different types of matter on their own is called diffusion.

Which are the 3 factors that affect the rate of diffusion?

1)Density

2)State of matter

3)Temperature

Which state of matter has the highest diffusion?

The rate of diffusion in liquids is higher than that of solids but the rate of diffusion of gases is the highest.

Define Density.

Mass per unit volume(kg/m3)

Define Rigidity.

The tendency of matter to retain its shape against external force.

Define compressibility.

The ability to reduce or lower its volume when force is applied.

Define Fluidity.

The ability of matter to flow(eg:-Gases and liquids)

Define Kinetic energy.

The energy possed by a particle due to motion.

What is the melting point of a solid?

the temperature at which a solid melts and converts into a liquid at atmospheric pressure. It is also called fusion.

What is the latent heat of fusion?

The amount of heat energy needed to convert 1kg of a solid into its liquid state at its melting point at atmospheric pressure.

What is the boiling point of a liquid?

the temperature at which a liquid turns into a gaseous state at atmospheric pressure. It is also called vaporization.

How can we liquify the atmospheric gases?

By applying pressure and decreasing the temperature.

Define sublimation.

the change of state directly from a solid to a gas

Define deposition.

The direct change of gas to solid.

What is dry ice? why is it called so?

Solid carbon dioxide. It is called so because it gets converted into a gaseous state on the decrease of pressure to atmosphere without coming into a liquid state.

What is fusion?

solid to liquid on heating.

Solidification

liquid to solid on cooling.

Vaporization

liquid to gas on heating.

Condensation

gas to liquid on cooling.

Sublimation

solid to gas

What is Evaporation?

The process of change of a liquid into vapor at any temperature below its boiling point.

Factors affecting rate of evaporation.

1)Temperature

2)Surface Area

3)Wind Speed

4)Humidity

Definition of Temperature, surface area, wind speed and humidity.

Temperature: Temperature increases- kinetic energy of the particles increases- hence the rate of evaporation is faster.

Surface area: surface area is more, a larger number of particles are exposed for evaporation- rate of evaporation is faster.

Wind speed: increase in wind speed- particles of water vapor move away- rate of evaporation is faster.

Humidity: Amount of water vapour in the atmosphere- increase in humidity means a decrease in evaporation.

How does evaporation cause cooling?

The particles of liquid absorb energy from surroundings to the region of energy lost evaporation. Absorption of energy from the surroundings makes the surroundings cool.

1)What is the boiling point of ice?

2)What is the melting point of ice?

1)100 degree celsius

2)273.15K