Chapter-A Journey through States of Water Science Curiosity class 6 in english Medium CBSE Notes

Chapter 8. A Journey through States of Water

Water is one of the most important natural resources on Earth. It exists in three states—solid, liquid, and gas. Heat and cooling change water from one state to another, making many natural processes possible.

Detailed Notes

States of Water

States of Water: Water exists in three physical states—solid, liquid, and gas.

Three States of Water

(i) Solid – Ice

(ii) Liquid – Water

(iii) Gas – Water Vapour

Characteristics of Water

(i) Water changes its state on heating or cooling.

(ii) All three states are forms of the same substance.

(iii) These changes are physical changes.

Properties of Solid, Liquid and Gas

Properties of Matter: Solid, liquid, and gas differ in shape, volume, and movement of particles.

Property	Solid	Liquid	Gas
Shape	Fixed	Takes the shape of the container	No fixed shape
Volume	Fixed	Fixed	No fixed volume
Can Flow	No	Yes	Yes
Compressibility	Very Low	Very Low	High

Melting

Melting: Melting is the process in which a solid changes into a liquid on heating.

Examples of Melting

(i) Ice changes into water.

(ii) Ice cream melts in summer.

(iii) Butter melts on heating.

Key Points

(i) Heat is absorbed during melting.

(ii) Only the state changes.

(iii) No new substance is formed.

Freezing

Freezing: Freezing is the process in which a liquid changes into a solid on cooling.

Examples of Freezing

(i) Water changes into ice.

(ii) Ice cubes are made in a freezer.

(iii) Lakes freeze in very cold regions.

Key Points

(i) Heat is removed during freezing.

(ii) Liquid water becomes solid ice.

(iii) It is the opposite of melting.

Evaporation

Evaporation: Evaporation is the process in which liquid water changes into water vapour.

Examples of Evaporation

(i) Drying of wet clothes.

(ii) Drying of wet roads.

(iii) Evaporation of sweat.

(iv) Drying of a mopped floor.

Characteristics of Evaporation

(i) Occurs at any temperature.

(ii) Takes place from the surface of water.

(iii) Absorbs heat from the surroundings.

Factors Affecting Evaporation

Factors Affecting Evaporation: The rate of evaporation depends on temperature, wind, surface area, and humidity.

Factor	Effect
High Temperature	Increases evaporation.
Large Surface Area	Increases evaporation.
High Wind Speed	Increases evaporation.
High Humidity	Decreases evaporation.

Cooling Effect of Evaporation

Cooling Effect of Evaporation: Evaporation absorbs heat from the surroundings and produces a cooling effect.

Examples

(i) Sweating cools our body.

(ii) Water in an earthen pot remains cool.

(iii) Hand sanitiser feels cool after use.

(iv) Sprinkling water cools the floor.

Condensation

Condensation: Condensation is the process in which water vapour changes into liquid water on cooling.

Examples of Condensation

(i) Water droplets on a cold bottle.

(ii) Dew on grass.

(iii) Fog on a bathroom mirror.

(iv) Water droplets on a vessel lid.

Key Points

(i) Water vapour loses heat.

(ii) Liquid water is formed.

(iii) It is the opposite of evaporation.

Cloud Formation

Cloud Formation: Clouds are formed when water vapour cools and condenses into tiny water droplets.

Steps of Cloud Formation

(i) Water evaporates due to the Sun's heat.

(ii) Water vapour rises into the atmosphere.

(iii) Vapour cools and condenses.

(iv) Tiny droplets join together to form clouds.

Key Points

(i) Clouds are made of tiny water droplets.

(ii) Heavy clouds produce rain.

The Water Cycle

Water Cycle: The water cycle is the continuous movement of water between the Earth's surface and the atmosphere.

Stages of the Water Cycle

(i) Evaporation

(ii) Condensation

(iii) Precipitation

(iv) Collection

Stage	Description
Evaporation	Water changes into water vapour.
Condensation	Water vapour forms clouds.
Precipitation	Water falls as rain, snow, or hail.
Collection	Water collects in rivers, lakes, and oceans.

Importance of the Water Cycle

(i) Recycles water in nature.

(ii) Maintains the water balance.

(iii) Provides fresh water for living organisms.

Importance of Water

Importance of Water: Water is essential for the survival of all living organisms.

Uses of Water

(i) Drinking

(ii) Cooking

(iii) Washing and cleaning

(iv) Farming and irrigation

(v) Industries

(vi) Producing electricity

Applications in Daily Life

Applications: The changes in the states of water can be seen in our daily life.

Examples

(i) Drying of clothes.

(ii) Cooling by sweating.

(iii) Making ice cubes.

(iv) Formation of clouds and rain.

(v) Cool water in an earthen pot.

Water Conservation

Water Conservation: Water conservation means using water wisely and avoiding its wastage.

Ways to Save Water

(i) Turn off taps after use.

(ii) Repair leaking taps.

(iii) Collect rainwater.

(iv) Use water carefully.

(v) Do not pollute water sources.

Quick Revision

(i) Water exists in three states—solid, liquid, and gas.

(ii) Melting changes solid into liquid.

(iii) Freezing changes liquid into solid.

(iv) Evaporation changes liquid into water vapour.

(v) Condensation changes water vapour into liquid.

(vi) Evaporation causes cooling.

(vii) Clouds are formed by condensation.

(viii) The water cycle continuously recycles water.

(ix) Water is essential for all living organisms.

(x) We should save and use water wisely.

Keywords

Melting: Change of solid into liquid.

Freezing: Change of liquid into solid.

Evaporation: Change of liquid into water vapour.

Condensation: Change of water vapour into liquid.

Water Cycle: Continuous movement of water in nature.

Water Conservation: Careful and wise use of water.

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