Matter in Our Surroundings

Chapter:- 1

Matter in Our Surroundings

Matter in Our Surroundings

What We Learn in Day 1

  • Matter in Our Surroundings
  • Matter is made of Particles
  • Evidence for particles in Matter

The process of dissolving sugar in water gives us two conclusions about the nature of matter

The existence of Brownian motion gives us two conclusions about the nature of matter

 Characteristics of Particles of Matter

Matter in Our Surroundings Anything which occupies space and has mass is called matter.

Matter is made of Particles

The particles which make up matter are atoms or molecules.

Evidence for particles in Matter

This movement of different particles among each other (on their own), so that they become mixed uniformly, is called diffusion. When sugar is added to water and stirred, it dissolves quickly.

When sugar dissolves sugar particles go into the spaces between the particles of water

When KMno4 dissolves KMno4 particles go into the spaces between the particles of water

The process of dissolving sugar in water gives us two conclusions about the nature of matter

  • That matter is made up of tiny particles, and
  • That the particles of matter are constantly moving.

The existence of Brownian motion gives us two conclusions about the nature of matter

  • That matter is made up of tiny particles, and
  • That the particles of matter are constantly moving. 

The zig – zag movement of the small particles suspended in a liquid (or gas) is called Brownian motion. Brownian motion increases on increasing the temperature.

Characteristics of Particles of Matter

  • They are very small.
  • They have spaces between them.
  • They are constantly moving.
  • They attract each other

Classification of Matter

Classification of Matter

  • On the basis of its physical state, such as solid, liquid or gas.
  • On the basis of its chemical composition, such as an element compound or mixture.

Matter

  • Solid
  • Liquid
  • Gas

Properties of Solids

  • Solids have a fixed shapes and a fixed volume.
  • Solids cannot be compressed much.
  • Solids have high densities. They are heavy.
  • Solids do not fill their container completely.
  • Solids do not flow.

Properties of Liquids

  • Liquids have a fixed volume but they have no fixed shape.
  • Like solids, liquids cannot be compressed much.
  • Liquids have moderate to high densities.
  • Liquids can take the shape of container in which they kept..
  • Liquids generally flow easily.

Properties of Gasses

  • Gases have neither a fixed shape nor a fixed volume.
  • Gases can be compressed easily
  • Gases have very low densities.
  • Gases fill their container completely.
  • Gases flow easily.

Why Solids, Liquids and Gases Have Different Properties

According to the kinetic theory of matter, the particles of matter are in continuous motion.

Some force of attraction tends to hold the particles together and control their movements.

To Show that Liquids do not have a Fixed Shape but they have a Fixed Volume

Does Gases have fixed shape and fixed volume why?

Why Solids and Liquids Cannot be Compressed but Gasses Can be Compressed Easily?

Diffusion

Diffusion is a property of matter which is based on the motion of its particles. Diffusion is fastest in gases and slowest in solids. The rate of diffusion increases on increasing the temperature.

The Common Unit of Temperature and SI Unit of Temperature

We use Celsius scale of temperature for measuring temperatures in our everyday life.

The laboratory thermometers which we use for performing science experiments the clinical thermometer which we use for measuring human body temperature

K = oC + 273

OoC = 273K

Change of state of matter 1

Change of state of matter

Why Solids, Liquids and Gases Have Different Properties

According to the kinetic theory of matter, the particles of matter are in continuous motion.

Some force of attraction tends to hold the particles together and control their movements.

To Show that Liquids do not have a Fixed Shape but they have a Fixed Volume

Does Gases have fixed shape and fixed volume why?

Why Solids and Liquids Cannot be Compressed but Gasses Can be Compressed Easily?

 

Diffusion

Diffusion is a property of matter which is based on the motion of its particles. Diffusion is fastest in gases and slowest in solids. The rate of diffusion increases on increasing the temperature.

Illustration

When someone opens a bottle of perfume in one corner of a room, its smell spreads in the whole room quickly. Why?

Solution

This happens because the particles of perfume (GAS) move rapidly in all the directions and mix with the moving particles of air in the room.

Illustration

Give reasons for the following observation. The smell of hot sizzling food reaches you several meters away, but to get the smell of cold food you have to go close.

Solution

The vapours of hot food diffuse in air readily but the cold food does not evaporate so fast so its particles cannot diffuse quickly in air and its smell cannot travel long distance.

The Common Unit of Temperature and SI Unit of Temperature

We use Celsius scale of temperature for measuring temperatures in our everyday life.

The laboratory thermometers which we use for performing science experiments the clinical thermometer which we use for measuring human body temperature

K = oC + 273
OoC = 273K

Illustration

Convert the following temperature to Celsius scale

  • 300K
  • 573K

Solution

For converting Kelvin to Celsius, the formula is

K – 273 = oC

  • 300K – 273 = 27oC
  • 573K – 273 = 300oC

Illustration

Convert the following temperature to Celsius scale

  • 293K
  • 470K

Solution

For converting Kelvin to Celsius, the formula is

K – 273 = oC

  • 293K – 273 = 20oC
  • 470K – 273 = 197oC

Illustration

Convert the following temperature to Kelvin scale

  • 25oC
  • 373oC

Solution

For converting Celsius to Kelvin, the formula is

oC + 273 = K

  • 25oC + 273 = 298K
  • 373oC + 273 = 646K

Change of state of matter

We can change the physical state of matter in two ways:

  • By changing the temperature, and
  • By changing the pressure.

Solid to Liquid Change: Melting

The process, in which a solid substance changes into a liquid on heating, is called melting (or fusion).

Illustration

For any substance, why does the temperature remain constant during the change of state?

 Solution

During the change of state, the temperature becomes constant, because the heat provided is utilized for breaking the attraction force between the particles of the substance. This happens at melting point (or boiling point) of the substance and the heat used is called the latent heat of fusion (or vaporization). During condensation or solidification, the vice-versa happens.

Liquid to Gas Change: Boiling (or Vaporization)

Place during boiling. The boiling of a liquid takes place at a fixed temperature. The temperature, at which a liquid boils and changes rapidly into a gas at atmospheric pressure, is called boiling point of the liquid.

When a liquid is heating, it changes its physical state and becomes a gas.

Illustration

What would be the temperature when water starts boiling?

Solution

As the water starts boiling, the temperature will be 100oC or 373 K.

Illustration

What is the temperature when all the water has boiled?

Solution

The temperature remains constant i.e., 100oC during its complete boiling process.

Illustration

Under which condition, we can boil water at room temperature?

Solution

We can boil water at room temperature 1 atomic pressure.

Illustration

At what temperature boiling takes place?

Solution

Boiling takes place only at boiling point.

Gas to Liquids Change:- Condensation

The process of changing a gas to liquid by cooling is called condensation.

Liquid to Solid Change: Freezing 

The process of changing a liquid into a solid by cooling is called freezing.

When a liquid is cooled its particles lose energy due to which they move slowly.  At this stage the liquid freezes and becomes a solid.

Illustration

Give reason for the observations.  We can get the smell of perfume sitting several meters away?

Solution

The smell o aroma of perfume reaches several meters away due to the fast diffusion of the gaseous particles of perfume through air.

Latent Heat

Latent Heat

The heat energy which has to be supplied to change the state of a substance is called its latent heat. Latent heat does not raise (or increase) the temperature.

Latent Heat is of Two Types

  • Fusion
  • Vaporization

Latent Heat of fusion (Solid to Liquid Change)

The latent heat of fusion (or melting) of a solid is the quantity of heat in joules required to convent 1 kilogram of the solid (at its melting point) to liquid, without any change in temperature.

Latent Heat of Vaporization

It is defined as heat required converting 1 mole of liquid into vapors completely at its boiling point.

Sublimation

The changing of a solid directly in to vapors on heating. And vapors’ into solid on cooling is known as sublimation. Sublimation can be represented as:

Ex:- Solids carbon dioxide

is a white solid called dry ice.

Gases Can be Liquefied by Applying Pressure and Lowering Temperature

Gases can be liquefied by applying pressure and lowering temperature.

Evaporation

The process of a liquid changing into vapour (or gas) even below its boiling point is called evaporation.

Factors Affecting Evaporation   

The evaporation of a liquid depends mainly on the following factors:

  • Temperature
  • Surface area
  • Humidity
  • Wind speed

Cooling Caused by Evaporation

The cooling caused by evaporation is based on the fact that when a liquid evaporates, it draws the latent heat of vaporization from ‘anything’ which it touches and makes it cool.

Change of state of matter

Change of state of matter

We can change the physical state of matter in two ways:

  • By changing the temperature, and
  • By changing the pressure.

Solid to Liquid Change: Melting

The process, in which a solid substance changes into a liquid on heating, is called melting (or fusion).

Liquid to Gas Change: Boiling (or Vaporization)

Place during boiling. The boiling of a liquid takes place at a fixed temperature. The temperature, at which a liquid boils and changes rapidly into a gas at atmospheric pressure, is called boiling point of the liquid.

When a liquid is heating, it changes its physical state and becomes a gas.

Gas to Liquids Change:- Condensation

The process of changing a gas to liquid by cooling is called condensation.

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Liquid to Solid Change: Freezing 

The process of changing a liquid into a solid by cooling is called freezing.

When a liquid is cooled its particles lose energy due to which they move slowly.  At this stage the liquid freezes and becomes a solid.