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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.
Created by: Hannah Cassidy