What is the difference between soft and hard water?
Soft water lathers easily with little soap whereas hard water uses a lot of soap to form a lather and produces scum.
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What is the difference between scum and scale?
Scum is formed when soap reacts with compounds in hard water and scale is produced when temporary hard water is heated.
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Why is it better to drink hard water rather than soft?
Hard water contains calcium compounds good for health of teeth, bones and reduces the risk of heart disease.
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How is permanent hard water softened?
In an ion-exchange column or by adding washing soda to it to remove the calcium and magnesium ions.
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How is temporary hard water softened?
Temporary hard water is heated to produce carbonate ions, water and carbon dioxide. The carbonate ions react with calcium and magnesium to produce precipitates that are deposited as scale.
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How does an ion exchange column work?
The column contains a resin, when hard water is passed through this resin calcium and magnesium ions become attached to it ad sodium or hydrogen ions replace them.
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How is water treated to make it safe to drink?
Filtration to remove solids then adding chlorine to kill microbes.
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How is pure water made?
By distillation which requires al ot of energy so if very expensive.
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Suggest one advantage and one disadvantage of softening hard water.
+ uses less soap and doesn't produce scum - reduces health benefits and costs a lot
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Why does hard water produce scum?
Soap reacts with calcium and magnesium ions to produce insoluble solids.
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How is scaled produced?
By heating temporary hard water.
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Whats the difference between temporary and permanent hard water?
Temporary hard water produces scale when heated but permanent doesn't.
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Other cards in this set
Card 2
Front
What is the difference between scum and scale?
Back
Scum is formed when soap reacts with compounds in hard water and scale is produced when temporary hard water is heated.
Card 3
Front
Why is it better to drink hard water rather than soft?
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