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 |