The document discusses the water cycle and the different states of water. It explains that water can exist as a solid, liquid, or gas and the processes by which it transitions between these states through melting, freezing, boiling, evaporation, and condensation. Temperature plays a key role in determining the state of water and the speed at which these processes occur. The water cycle replenishes the Earth's water supply as the sun drives evaporation and transpiration, which leads to condensation and precipitation.
3. Introduction Covers three-quarters of the earth surface All living things need water to survive. Water exists in three different states: Solid Liquid Gaseous
5. Water in the Liquid State Most of the Earth’s water is sea water. raindrops dew clouds
6. Water in Gaseous State Water vapour Steam Similarities: Both are colourless Both are water in gaseous state Differences At any temperature 100 0 C
7. Changing States of Water: Heat Gained Solid to liquid: Melting (0 0 C) Liquid to Gaseous : Evaporation : Boiling (100 0 C)
8. Changing States of Water: Heat Loss Liquid to Solid: Freezing (0 0 C) Gaseous to Liquid : Condensation
9. Changing States of Water: Heat Loss Liquid to Solid: Freezing (0 0 C) Liquid to Gaseous : Condensation
10. Melting From solid to liquid Gains heat Happens at 0 0 C Ice to water Temperature stays the same Heat gained to change state of water from solid to liquid State of water during melting: solid and liquid
11. Freezing From liquid to solid Heat loss from water to the surrounding Happens at 0 0 C Water to Ice Temperature stays the same
12. Boiling From liquid to gaseous Gains Heat Happens at 100 0 C Water to Steam Temperature stays the same Heat gained to change state of water from liquid to gaseous State of water: liquid and gaseous
13. Evaporation From liquid to gaseous Gains heat Evaporation happens all the time and at any temperature. Water to Water Vapour
14. Condensation From gaseous to liquid Loses heat Condensation happens due to temperature difference Water Vapour to Water Steam to Water
15. Condensation Faster Slower More water droplets Less water droplets (100 0 C) (10 0 C) (100 0 C) (70 0 C)
16. Evaporation The rate of evaporation depends on a few factors: Presence of wind Humidity Temperature Area of exposed surface
17. Presence of Wind Water evaporates faster in the presence of wind. When water evaporates, water vapour gathers above the surface of the water . Wind will carry the water vapour away, making space for more water to rise.
18. Humidity (Amount of water vapour in the air) High humidity: Large amount of water vapour in the air Higher humidity Slower rate of evaporation There is little or no space in the air for any more water vapour when humidity is high.
20. Area of Exposed Surface The larger the area of the exposed surface, the greater the amount of evaporation. Larger exposed surface area Smaller exposed surface area
21. Area of Exposed Surface 0 fold 1fold 2 folds Increase rate of evaporation
25. Water Cycle Respiration Animals give out water vapour Stage 1: Evaporation Heat from sun evaporate water from rivers, lakes and sea Transpiration Plants give out water vapour through stomata of leaves
26. Water Cycle Stage 2: Condensation Water vapour rises into the air and condenses into water droplets
27. Water Cycle Stage 3: Precipitation Clouds become to heavy and fall as rain to the ground