Question | Answer |
What is the boiling point of water ? | 100 degrees Celsius |
What is the freezing point of water ? | 0 degrees Celsius |
What is hard water ? | Water that does not easily form a later with soap. |
What is soft water ? | Water that easily forms a later with soap. |
What causes water hardness ? | The presence of calcium and/or magnesium ions. |
How many stages are there in the water treatment cycle ? | 5 (screening, settling, filtration,chlorination and fluoridation) |
What is screening ? | Screening involves using a wire mesh to filter out large, insoluble particles (e.g. twigs/branches). |
What is settling ? | Settling involves using settling beds to remove smaller insoluble particles. |
What is filtration ? | Filtration involves filtering the water through beds of sand & gravel to remove small insoluble particles. |
What is chlorination ? | Chlorination involves adding chlorine to kill bacteria. |
What is fluoridation ? | Fluoridation involves adding fluoride for healthy teeth. |
How is hardness removed from water ? | Hardness in water is removed by distillation or using an ion exchange resin. |
How does an ion exchange resin work ? | Ion exchange resin works by exchanging the calcium ions which cause hardness with hydrogen ions. |
What are the advantages of hard water ? | Advantages of hard water include that it tastes better, and provides calcium. |
What are the disadvantages of hard water ? | Disadvantages of hard water include that it causes limescale, and wastes soap. |