Chemistry- hard and soft water

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what is water termed hard or soft water according to?
which substances are dissolved in it
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what does hard water contain?
dissolved calcium (ca2+) and magnesium (Mg2+) ions. the compounds usually dissolve when acidic water comes into contact with rocks.
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describe temporary hard water
contains calcium and/or magnesium hydrogen carbonates. Hardness can be removed by boiling
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describe permanent hard water
contains calcium and/or magnesium sulfates and/or chlorides. Hardness cannot be removed by boiling.
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explain testing for hardness in water
can tell difference between h and s water by seeing how well water lathers when soap is added+waker shaken.Difficult to produce lather in hard water but soft water lathers easily. If water sample produce more lather only after it has been boiled-te
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how does boiling remove temporary hardness?
bc it converts the hydrogen carbonates of calcium and magnesium into carbonates which are insoluble and form a precipitate.-cause of limescale(fur) in kettles+hot water pipes.
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how can permanent hardness of water be removed?1st way.
adding sodium carbonate.Calcium and magnesium ions bond with carbonate ions-meaning less detergent has to be used.It is cheap but desposits still form.
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how can permanent hardness of water be removed?2nd way.
passing water through an ion exchange column.-removes the calcium+mag ions+replaces them with sodium ions which don't cause hardness.it is effective but expensive.
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name 3 advantages of hard water
many ppl think tastes better than soft water.c and m are essential minerals in the diet+hard water provides them.M in hw may give some protection against heart disease.
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name 3 disadvantages of hard water
temporary hard water can produce deposits which clog+damage hot water pipes,boilers,kettle elements.HW requires more soap or deterrent to clean effectively.treating permanent hw in other to save on detergent can produce deposits on washed clothes.
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what are signs of hard water?
when the same amount of soap gives a scum and hardly any lather.
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what are signs of soft water?
when the tap water lathers easily with soap.
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finished:)x
x
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Other cards in this set

Card 2

Front

what does hard water contain?

Back

dissolved calcium (ca2+) and magnesium (Mg2+) ions. the compounds usually dissolve when acidic water comes into contact with rocks.

Card 3

Front

describe temporary hard water

Back

Preview of the front of card 3

Card 4

Front

describe permanent hard water

Back

Preview of the front of card 4

Card 5

Front

explain testing for hardness in water

Back

Preview of the front of card 5
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