Water

Question 1

What are the main ions that cause water hardness?

Answer 1

Calcium & Magnesium ions

Question 2

Give two health benefits of drinking hard water

Answer 2

Good for teeth & bones and less risk of heart disease

Question 3

Describe how you can remove permanent hardness from water

Answer 3

Adding sodium carbonate to the water makes insoluble precipitates of the calcium & Magnesium ions OR use an ion exchange column. Here the Ca & Mg ions are exchanged for Na & H ions

Question 4

Describe how you could use Titration to compare two types of water

Answer 4

Fill a Burette with soap solution, run in 1ml of soap into your water sample. Shake for 10 seconds and repeat until a good lasting lather is formed. Record how much soap solution was needed. Repeat steps for second sample and compare results

Question 5

What are the advantages of adding Fluoride & Chloride to water?

Answer 5

Reduce tooth decay, prevent disease,

Question 6

What are the disadvantages of adding F & Cl to water

Answer 6

Some studies suggest a link between Cl in water & certain cancers. High doses of F also cause cancer & bone problems

Question 7

Explain why tap water is not produced by distillation

Answer 7

Water would need to be boiled into steam and then condensed, this would use a lot of energy and be very expensive. Also use of fossil fuels to produce the energy needed to boil the water