Water

Question 1

Test for presence of water

Answer 1

Anhydrous copper (ii) sulfate
white –> blue

Anhydrous cobalt (ii) chloride
Blue–> pink

Can be reserved by heating. Heating breaks the chemical bond between the water and salt

Question 2

Test for purity of water

Answer 2

Test for the boiling point
Pure water will boil at a sharp, constant, and fixed temperature of 100 celsius

Impure water will boil over a range of temperatures.

Question 3

Distilled water

Answer 3

deionized water
tap water is boiled to remove the contaminants and minerals to produce distilled water

Question 4

Dissolved oxygen in natural water

Answer 4

Enters water through photosynthesis and diffusion from the atmosphere

high temperature decreases the amount of dissolved oxygen

salt water has less dissolved oxygen than fresh water

Question 5

Plastics harm aquatic life

Answer 5

• discarded fishing nets trap marine animals and sea birds
• Sea animals may choke on discarded plastic bags
• microplastics can damage the digestive systems of marine animals

Question 6

Harmful microbes can cause

Answer 6

diarrhea, cholera

Question 7

Nitrates and phosphates damage aquatic life

Answer 7

1. fertilisers from soil washed off by rain into lakes and rivers
2. fertilisers cause algae to grow on the surface of the water, blocking sunlight for the plants
3. Decrease the amount of dissolved oxygen for animals and plants
4. bacteria feed on dead algae and use up dissolved oxygen
5. plants and animals die

aka eutrophication