Edexcel C3 Hard Water
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
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| What ions are in hard water? | Ca+2 and Mg+2
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| What is the effect of hard water? | Produces Scum and Scale
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| What is Scale? | the deposit left behind after boiling the kettle in a hard-water area. It is Calcium Carbonate
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| What is Scum? | The deposit made from soap reacting with the Ca+2 ions
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| Which type of water creates the most lather with soap: hard or soft water? | Soft
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| What is temporary hardness? | Caused by having bicarbonate ions dissolved in water
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| What is permanent hardness? | Caused by having sulfate ions dissolved in water
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| How can you remove temporary hardness? | Simply boiling
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| How can you remove permanent hardness? | Ion exchange
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| How does ion exchange work? | where Ca+2 ion are replacing Na+ on a resin; the Na+ ions are replacing the Ca+2 in water
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| Why should you treat your water if you live in a hard-water area? | Overtime, limescale will build up in washing machine pipes and block them
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| Why does the water become hard again after having used an ion-exchange resin for a while? | All the Na+ions have been replaced on the resin
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| How do you regenerate the resin? | Pass a concentrated brine (NaCl solution) through the resin will force the Ca+2 out of the resin and the resin will carry Na+ ions again
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| What is the concentration of calcium ions in a sample of water that has: 0.4 g of calcium ions dissolved in 2 dm3 of the water | 0.4/2=0.2 gdm−3
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| What is the concentration of calcium ions in a sample of water that has: 0.25 g of calcium ions dissolved in 5 dm3 of the water? | 0.25/5=0.05 gdm−3
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| A sample of hard water has a concentration of calcium ions of 0.12 g dm-3. What mass of calcium ions would there be in a 200 cm3 glass of the water? | 0.12 x 0.2dm3 = 0.024g
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| What is the formula to work out concentration? | concentration (g.dm-3) = mass(g) / volume(dm3)
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Created by:
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