2. Water By Neil Bronks

3. Water is important 70% of the earth 89% of the human body Only 3% is fresh and most of that is in the polar ice caps

4. Water is a compound Chemically bonded atoms of Oxygen and Hydrogen H H H H O O O H H O H H 2H 2 + O 2 2H 2 O

5. Ice Floats Most substances contract and get denser as they become a solid More dense solid sinks

6. Ice Floats Ice expands and so floats on water. Lucky for us Less dense solid floats

7. Frozen Pond

8. Water Cycle

9. Water Treatment Screening - Clean water passes through the screen and large objects do not

10. Sedimentation Alum (Aluminium Sulphate) is added that makes all the dirt stick together. Most sinks

11. Then Filter through sand

12. Add Chlorine Kills the bacteria Cl

13. Add Fluorine Prevents tooth decay F

14. Water Treatment Screening - Clean water passes through the screen and large objects do not pass Sedimentation - Aluminium Sulphate is added. It is mixed slowly and then allowed to settle. Filtration – passes through sand Add chlorine to kill bacteria. Add flourine to prevent tooth decay.

18. Desalination Removing salt Clear Plastic Sea Water Pure Water Stone

19. Electrolysis of Water

20. Water separated into gases using electricity Some acid must be added to increase conduction

21. Algal Bloom Too much fertiliser or food waste can feed algae causing a harmful algal bloom This uses up all the oxygen and kills fish

22. Hard and soft water Add soap and mix Add Soap solution Hard Water Few Bubbles Oily scum Soft Water Lots of Bubbles

23. Hard Water Contains dissolved calcium and magnesium ions Forms scum when soap is used Scale on inside of pipes and kettles

24. Where hard water comes from Acid Rain Limestone Water dissolves the limestone (Calcium Carbonate) and the calcium ions make the water hard Water that runs off straight to rivers and lakes is soft water

25. Removing Hardness from water Distillation Ion exchange with Zeolite resins Soft water better for industry and plumbing Hard water better for your heart

26. Advantages and Disadvantages of Hard and Soft Water AdvantageDisadvantage Hard Good for Heart and Beer Scale in pipes Soft Good for washing clothes Girl children

27. Summary

28. H/w P 250 Q 1,2,4,5,6,8.