Class 6 Science Chapter 8 A Journey Through States of Water Notes & Summary in English for CBSE students
CBSE Class 6 Science Chapter 8 Notes & Summary in English for “A Journey Through States of Water” (based on NCERT textbook Curiosity ).
Chapter 8 – A Journey Through States of Water Complete Notes
(Complete Notes + Concept-wise Explanation + Summary CBSE Class 6 Science – Curiosity Book)
CLASS 6 SCIENCE – CHAPTER 8 A Journey Through States of Water
1. Introduction to Water and Its States
Water is one substance but appears in different forms in our daily life.
Examples:
• Ice (solid)
• Water (liquid)
• Water vapour/steam (gas)
When Aavi and Thirav discuss ice and water, they initially think they are different substances. After experimenting, they understand:
Ice and water are the same substance in different states.
When water freezes, it becomes ice.
When ice melts, it becomes water.
2. Ice and Water as the Same Substance
Activity 8.1 shows that an ice cube melts to form water.
This proves:
Ice and water are the same substance in different states (solid and liquid).
Properties:
• Water flows easily
• Ice does not flow
• Water takes the shape of a container
• Ice retains its shape
3. Disappearance of Water (Evaporation)
Children observe puddles after rain, but later the water disappears.
Possible reasons they think of:
• Water is absorbed by soil
• Water seeps through surfaces
• Water evaporates
Evaporation is the key concept here.
Evaporation
Evaporation is the process of water changing into water vapour.
It happens:
• Even at room temperature
• Faster when heated
• Faster on windy/hot days
Everyday examples:
• Drying clothes
• Wet floor drying after mopping
• Sweat drying
• Water sprinkled on a hot tawa disappearing
4. Investigating Evaporation (Activity 8.2)
A spoon of water is kept on a steel plate.
Observations:
• Water does not seep through steel
• Water slowly disappears
• Water changes into water vapour
Thus:
Water disappears from surfaces because it evaporates, not because it seeps through.
5. Steam and Water Vapour
Steam is visible due to tiny droplets of liquid water carried by the vapour.
Pure water vapour is invisible.
6. Condensation (Water Droplet Formation)
When Aavi and Thirav place cold water with ice in a tumbler, water droplets appear on the outer surface.
Where do the droplets come from?
Not from inside the glass.
Not due to leakage.
They come from the air outside the glass.
Condensation
Condensation is the process of water vapour changing into liquid water when it touches a cold surface.
Daily examples:
• Dew drops on leaves
• Water droplets on cold bottles
• Fog on mirrors
• Drops under the plate covering boiling water
7. Activity 8.4: Measuring Condensation
A tumbler with ice water is placed on a digital balance.
Weight increases slowly because:
• Water vapour condenses on the tumbler
• Extra water collects on outer surface
Marking the water level proves:
Water does not seep through the glass
The droplets come from condensation of atmospheric vapour.
8. States of Water: Solid, Liquid, Gas
Water exists in three states:
1. Solid (Ice)
• Fixed shape
• Does not flow
• Does not spread
2. Liquid (Water)
• Flows
• Takes shape of container
• Fixed volume
• Spreads slightly on surfaces
3. Gas (Water Vapour)
• No fixed shape
• Spreads to fill entire space
• Invisible
9. Changing States of Water
Water changes its state when heated or cooled.
Melting
Solid → Liquid
Example:
Ice melts to water.
Freezing
Liquid → Solid
Example:
Water freezes into ice.
Evaporation
Liquid → Gas
Example:
Water evaporates into water vapour.
Condensation
Gas → Liquid
Example:
Water vapour cools into water droplets.
10. Diagram (Activity 8.6) Explanation
Solid (Ice)
Melts →
Liquid (Water)
Evaporates →
Gas (Water Vapour)
Condenses →
Liquid
Freezes →
Solid
This cycle continues naturally in the environment.
11. Factors Affecting Evaporation
Evaporation happens faster when:
1. Area exposed is more
Water spreads → faster evaporation.
2. Air movement (wind) is faster
Wind blows away the vapour → faster drying.
3. Temperature is higher
Heat gives energy → faster evaporation.
4. Humidity is low
Less vapour in air → more evaporation.
Clothes dry:
• Faster in sunlight
• Faster in wind
• Slower on rainy/humid days
12. Cooling Effect of Evaporation
When water evaporates, it takes heat from surroundings, causing cooling.
Examples:
• Earthen pot (matka) cools water
• Sweat cools the body
• Water sprinkled on roof cools it
• Sanitiser feels cool because its liquid evaporates
13. Pot-in-Pot Cooler (Activity 8.9)
Two earthen pots are used with sand in between.
Water in sand evaporates causing cooling.
This method preserves fruits and vegetables for many days.
14. Why Water Vapour Rises Up
Water vapour is lighter than air, so it rises like a gas balloon.
15. How Clouds Form and How It Rains
When warm air rises:
• It cools
• Water vapour condenses
• Tiny water droplets form clouds
• Droplets join to form bigger drops
• Heavy drops fall as rain
Under special conditions:
• Snow
• Hail
16. Dust Particles and Cloud Formation (Activity 8.10)
When dust or smoke particles are present, water vapour condenses around them.
This makes cloud formation easier.
17. Water Cycle (Activity 8.11)
The movement of water between Earth and atmosphere is called the water cycle.
Processes involved:
• Evaporation
• Condensation
• Precipitation (rain, hail, snow)
• Collection in rivers, oceans, lakes
• Groundwater storage
Water cycle is continuous and keeps water available on Earth.
18. Importance of Water Conservation
Water is limited.
Most water is in oceans and cannot be used directly.
Increasing population increases demand.
We must:
• Use water carefully
• Avoid wastage
• Prevent pollution of water bodies
Summary of Chapter 8
• Water exists in solid, liquid and gaseous states.
• Ice and water are the same substance in different states.
• Evaporation converts liquid water to vapour.
• Condensation converts vapour to liquid water.
• Water changes state by heating and cooling.
• Evaporation causes cooling.
• Evaporation is faster with heat, wind, larger area, and low humidity.
• Clouds form by condensation of water vapour.
• Rain, hail and snow bring water back to Earth.
• Water cycle keeps water circulating.
• Water must be conserved responsibly.
Concept-Wise Quick Revision
Evaporation
• Liquid to gas
• Needs heat
• Faster on hot, windy, sunny days
• Slower on humid, rainy days
• Causes cooling
Condensation
• Gas to liquid
• Happens on cold surfaces
• Forms dew, fog, droplets on cold tumbler
Melting
• Solid to liquid
• Ice melts at room temperature or when heated
Freezing
• Liquid to solid
• Happens when temperature falls
States of water
• Ice – solid
• Water – liquid
• Vapour – gas