Last Min Chem

Question 1

Impacts of ozone

Answer 1

Can enter plant leaves through stomas and cause a reduction in photosynthesis decreasing plant growth

Question 2

Benefits of ocean acidification .

Answer 2

Promotes photosynthesis of aquatic plants and reducing co2 in atmosphere

Question 3

What are the chlorination of water equations?

Answer 3

Cl2 + H2O <-> HOCL + H+ +Cl-
And
HOCl + H2O <-> ClO- +H3O+
And
ClO- + H2O <-> HClO + OH-

Question 4

Nitrification equations

Answer 4

N2 + O2 -> 2NO
2NO + O2 -> 2NO2
2NO2 + H2O -> HNO3 + HNO2

Question 5

Ocean acidification equations

Answer 5

ÇaCO3 + 2H+ <-> CO- + H2O + Ca2+
CO32- + H3O+ <-> HCO3- + H2O

Question 6

Describe how nitrifying bacteria work

Answer 6

Nitrifying bacteria in the soil oxidise ammonia (NH3) and ammonium ions (NH4+) into nitrite ions (NO2-) and nitrate ions (NO3-).
NH3/NH4+ -> NO2- -> NO3-

Question 7

Describe denitrification

Answer 7

Denitrifying bacteria in the soil reduces the nitrate ions (NO3-) to nitrogen gas under anaerobic conditions.
NO3- -> N2

Question 8

Describe the process of synthetic nitrogen fixation

Answer 8

The synthetic Haber process converts atmospheric nitrogen (N2) to ammonia (NH3) under high pressure and temperature.
N2 + 3H2 -> 2NH3

Question 9

Describe eutrophication

Answer 9

The use of fertilisers can lead to eutrophication, especially after periods of heavy rainfall.
Excess nitrogen and phosphorus from fertilisers, detergents (contain phosphate groups) or sewage can be leached from soils into waterways e.g. rivers and lakes causing eutrophication
The increase in available nutrients promotes the excessive growth of aquatic plants including photosynthetic microbes including; algae and bacteria. These microbes form a bloom which prevents sunlight from reaching into the waterway.
Aquatic plants underneath the bloom do not receive sunlight and are unable to photosynthesise causing them to die.
Aerobic bacteria decompose the dead plant matter, further depleting the oxygen supply in the water and causing the death of aquatic organisms (plants, fish etc.).
When the oxygen supply is fully depleted, anaerobic bacteria decompose the plant and animal remains generating products that are toxic to the water, making the water even less habitable for the remaining organisms.

Question 10

Describe the steps of froth flotation

Answer 10

1. The powdered mineral and gangue are mixed with water to form a slurry.
2. Frothing agents and collectors are added.
3. Air is blown through the slurry and it is stirred to create bubbles which the minerals attach to and float to the surface.
4. Froth containing the mineral is skimmed off and excess water is removed.
5. Waste gangue sink to the bottom.