Hard water reacts with soap to form scum so more soap is needed to form a lather.
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What are the advantages of hard water?
Calcium compounds are good for your teeth and bones. Also they also help to reduce heart disease.
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What are the 2 main compounds that hard water usually contains?
Calcium and magnesium.
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There are 2 types of hard water: permanent hard water and temporary hard water. What is the difference?
Permanent remains hard even after boiling but temporary softens after boiling.
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What happens when temporary hard water is heated?
It can produce scale that reduces the efficiency of heating systems and kettles.
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What is scale?
Temporary hard water contains hydrogencarbonate ions (HCO3-) that decompose on heating to produce carbonate ions which react with calcium and magnesium ions to form precipitates.
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What 2 ways can soften water?
Adding sodium carbonate or using an ion exchange column
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Describe what happens when you add sodium carbonate to hard water.
The sodium carbonate reacts with the calcium and magnesium ions to form a precipitate of calcium carbonate and magnesium carbonate.
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Describe what happens when you use an ion exchange column to soften water.
They contain hydrogen ions or sodium ions, which replace the calcium and magnesium ions when hard water passes through.
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What should water be like, for humans to safely drink it?
Low in dissolved salts and microbes.
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What do water filters containing carbon, silver and ion exchange resins do?
Remove some dissolved substances from tap water to improve the taste and quality.
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Why may chlorine be added to water?
To reduce mircrobes.
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Why may flouride be added to water?
To improve dental health
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How can pure water be produced? and what is the drawback of doing this?
Distillation - Large amounts of energy needed, so is very expensive.
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Other cards in this set
Card 2
Front
What are the advantages of hard water?
Back
Calcium compounds are good for your teeth and bones. Also they also help to reduce heart disease.
Card 3
Front
What are the 2 main compounds that hard water usually contains?
Back
Card 4
Front
There are 2 types of hard water: permanent hard water and temporary hard water. What is the difference?
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