Water

Question 1

PROPERTIES OF WATER

Answer 1

Density
Specific heat capacity
Boiling point
Solvent nature

Question 2

disadvantages of hard water.

Answer 2

• Leaves scum on baths
• May leave clothes with a ‘hard’ feeling
  after washing
• Wastes soap as hard water produces
  little lather
• Causes kettles to ‘fur up’ and pipes to
  be blocked up

Question 3

Advantages of hard water

Answer 3

• Has a taste most people prefer
• Provides calcium compounds for teeth
  and bones
• Less likely to dissolve lead pipes (lead
  is poisonous)
• Good for brewing beer

Question 4

Temporary hardness

Answer 4

caused by the presence of calcium hydrogencarbonate

calcium carbonate or magnesium carbonate.

Question 5

Permanent hardness

Answer 5

caused by the presence of calcium sulphate

Question 6

Ways to soften water

Answer 6

1. Boiling- expensive; only removes temporary hardness
2. Addition of calcium hydroxide- quite cheap; only removes temporary hardness
3. Addition of sodium carbonate (washing
   soda)- Fairly cheap; removes all types of
   hardness
4. Distillation- Very expensive; removes all types of
   hardness
5. Use of an ion-exchange resin- The resin is expensive but can be used over and over again; removes all types of hardness