Chem 3.2 0.0 / 5 ? ChemistryGCSEAQA Created by: hallie proctorCreated on: 08-05-13 20:48 What is the difference between soft and hard water? Soft water lathers easily, hard water uses more soap and produces scum. 1 of 9 What is the difference between scum and scale? Scum is formed when soap reacts with compounds in ahrd water. Scale is the product of when temporary hard water is heated. 2 of 9 Why is it better to drink hard water rather than soft water? Hard water contains calcium compounds which are good for health, for the development of bones and teeth. 3 of 9 What is meant by 'temporary hard water'? Water that is softened by heating or boiling (and forms scale when its heated) 4 of 9 How does an ion-exchanging resin soften hard water? They remove the calcium and magnesium ions from hard water and replaces them (exchanges) for sodium or hydrogen ions. 5 of 9 How is drinking water treated to make it safe to drink? Sedimentation and filtration to remove solids and kill microbes, disinfecting using chlorine. 6 of 9 Explain why distillation is not used to treat mains tap water. It requires a large amount of energy so would be very expensive. Tap water does not need ot be pure to drink, just free from harmful substances. 7 of 9 Suggest one advantage and one disadvantage of softening hard water. Adv: uses less soap, doent produce scum, reduces the effect on heating sytems. Disad: reduces health benefits, costs money. 8 of 9 What would be the consequences of not adding chlorine and fluoride to tap water? No chlorine: increased health risks, more spreading of diseases. No fluride: more tooth decay, poor dental health. 9 of 9
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