C3 Revision

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What happens when temporary hard water is boiled?
When heated, the calcium hydrogencarbonate decomposes to form calcium carbonate which is insoluble. This solid is the 'limescale' on your kettle.
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How can both temporary and permanent hard water be softened?
Both types of hardness can be softened by adding sodium carbonate to it. The added carbonate ions react with the calcium and magnesium ions to make an insoluble precipitate of calcium carbonate and magnesium carbonate.No more Ca & Mg ions-so not hard
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Describe how the ion exchange column works?
The columns have lots of sodium or hydrogen ions inside them which are trapped on insoluble resins. The sodium or hydrogens ions are 'exchanged' with calcium or magnesium ions in the water that runs through the column. The water is no longer hard.
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What is hard water?
Hard water contains calcium and magnesium ions.
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What is scale?
Scale is calcium carbonate or magnesium carbonate.
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What is scum?
Scum is calcium stearate or magnesium stearate.
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Other cards in this set

Card 2

Front

How can both temporary and permanent hard water be softened?

Back

Both types of hardness can be softened by adding sodium carbonate to it. The added carbonate ions react with the calcium and magnesium ions to make an insoluble precipitate of calcium carbonate and magnesium carbonate.No more Ca & Mg ions-so not hard

Card 3

Front

Describe how the ion exchange column works?

Back

Preview of the front of card 3

Card 4

Front

What is hard water?

Back

Preview of the front of card 4

Card 5

Front

What is scale?

Back

Preview of the front of card 5
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