Chapter 5: Water and Solution

Question 1

State water’s characteristics.

Answer 1

Pure water is colourless, odourless and tasteless.

Question 2

What is the density of water?

Answer 2

1 g cm^3

Question 3

What is surface tension?

Answer 3

Surface tension is a result of cohesive force between the molecules of water at the surface that allows insects to stay afloat on water

Question 4

What is capillary action?

Answer 4

Cohesive force and adhesive force between water molecules and the cell walls of xylem allow water to be drawn up from the roots to the leaves of plants

Question 5

What is produced at the anode part of electrolysis?

Answer 5

Oxygen

Question 6

What is produced at the cathode part of electrolysis?

Answer 6

Hydrogen

Question 7

What is a solute?

Answer 7

A solute is a substance that can dissolve in a

liquid,

Question 8

What is a solvent?

Answer 8

A solvent is a liquid that dissolves a substance.

Question 9

What are a dilute solution, concentrated solution and saturated solution?

Answer 9

Dilute solution:
• Less amount of solute in the solvent
• Can dissolve more solute

Concentrated solution:
• More amount of solute in the solvent
• Can dissolve less solute

Saturated solution:
• Excess amount of solute in 
the solvent
• Cannot dissolve anymore 
solute and form precipitate

Question 10

What is a suspension?

Answer 10

Suspension is a cloudy mixture formed from undissolved solute particles in a solvent.

Question 11

What is solubility?

Answer 11

Solubility of a solute is the maximum amount of the solute that can dissolve in 100 ml of solvent at a specific temperature.

Question 12

What are the factors that affect the rate of solubility?

Answer 12

Temperature
Rate of stirring
Size of solute

Question 13

What is a colloid?

Answer 13

A colloid is a mixture of two or more solutes dispersed evenly in a solvent.

Question 14

State 5 organic solvents and their uses.

Answer 14

Alcohol: Perfume, Antiseptic
Kerosene: Lamp oil
Turpentine: Nail varnish, Lacquer
Acetone: Paint remover, Paint thinner 
Ether: Oil extractor

Question 15

State 4 water purification methods.

Answer 15

• Boiling
• Filtration
• Distillation
• Chlorination

Question 16

Why is water purification necessary?

Answer 16

Water purification is essential to remove odour, colour, taste, microorganisms and harmful chemicals so it is safe for consumption.

Question 17

What does filtration do?

Answer 17

Removes large suspended particles such as tree branches and leaves

Question 18

What does coagulation do?

Answer 18

• Alum is added so that mud particles stick together and sink to the bottom of the tank
• Slaked lime (calcium hydroxide) is added to reduce the acidity of water

Question 19

What does oxidation do?

Answer 19

Increases oxygen content in the water to get rid of unpleasant smell and taste

Question 20

What does sedimentation do?

Answer 20

Suspended particles deposit at the bottom of the tank

Question 21

What do chlorination and fluoridation do?

Answer 21

• Chlorine is added to kill microorganisms in water

* Sodium fluoride is added to prevent tooth decay

Question 22

State laws to ensure industrial waste is treated

before being discharged into the river.

Answer 22

• Environmental Quality (Scheduled Wastes) Regulations 2005
• Environmental Quality (Industrial Effluent) Regulations 2009
• Environmental Quality (Sewage) Regulations 2009