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Water
Revision of Water chapters
| Question | Answer |
|---|---|
| Name the two elements water is made up of. | Hydrogen and Oxygen |
| Name the two scientific processes that occur during the water cycle that cause water vapour to be in the atmosphere. | Evaporation and Transpiration |
| Name the five stages of water treatment. | Screening, Settling, Filtration, Chlorination and Flouridation |
| Name the chemical added to water during the settling phase of water treatment. | Aluminium Sulphate |
| What is the purpose of the chlorination phase of water treatment? | Killing bacteria |
| What is the purpose of the fluoridation phase of water treatment? | To prevent tooth decay |
| What is the density of pure water? | 1.0 g/cm3 |
| What happens the boiling point of water if you reduce the pressure? | It lowers |
| How do you test for the presence of water? | Cobalt Chloride Paper (Blue -> Pink) or Anhydrous Copper Sulphate (White -> Blue) |
| Name the process of separating water into its elements using electricity. | Electrolysis |
| Name the apparatus commonly used in the laboratory to demonstrate electrolysis. | Hoffmann Voltameter |
| Which gas collects over the positive electrode in electrolysis? | Oxygen |
| Why is a little acid added to the water during electrolysis? | To improve the conductivity of the water |
| What is hard water? | Water that does not easily form a lather with soap. |
| What causes hardness in water? | Dissolved Calcium and Magnesium Ions |
| Name two methods of removing hardness from water. | Boiling, Ion Exchange Resin or Distillation |
| List some advantages of hard water. | Good source of calcium for teeth and bones, Nicer taste, Good for brewing |
| List some disadvantages of hard water. | Blocks pipes, Leaves scale on kettles, Wastes soap, produces scum |
| What scientific process would you use to show water contains dissolved solids? | Evaporation |