B: Chemistry and the Environment

Question 1

Xenobiotics

Answer 1

compounds that are present in living organisms but should not normally be found there

• eneter the water supply in various ways eg urine washing, disposal of unwanted medicines –> carried to sewage plants –> released to environment due to improper treatment
  
  • pharmaceuticals found in drinking water
  • release of antibodies can result in increased resistance of bacteria

Question 2

Biodegradable Plastics (pros/cons)

Answer 2

• can be broken down by microorganisms

Pros

• renewable
• can be broken down by microorganisms

Cons

• weaker than normal plastics –> decompose quicker
• corn used for plastic rather than for food

Question 3

Host-Guest chemistry

Answer 3

• the creation of syntehtic host molecules that mimic some of the actions performed by enzymes in cells
  
  • substrate does not form covalent bonds in the active site of the enzyme –> held in place by other forces eg H bonds, LDFs, ionic
• removes toxis materials such as heavy metals
  
  • calixarenes are used to remove highly radioactive caesium ions / uranium ions from water

Question 4

Uses of Enzymes

Answer 4

• Helps breakdown oil spills, treat industrial waste and in biological detergents
  
  • immobilized enzymes (attached to a filter) can be used in treating waste water
  • biological detergents help breakdown fats and proteins
    
    • saves energy by cleaning at lower temps

Question 5

Biomagnification

Answer 5

The increase in concentration of a substance as it passes up a food chain

Question 6

Biomagnification - DDT

Answer 6

• pesticides
• absorbed by microscopic plants
• larger and larger fish eat it
• birds eat the fish
• weaken egg shells so they are unable to support the weight of the mother

Question 7

Biomagnification - Mercury

Answer 7

• Waste incineration, gold mining
• absorbed by microorganisms in water
• increases in concentration until it reaches tuna
• humans eat tuna

Question 8

Green Chemistry

Answer 8

An approach to chemical research and chemical industrial processes that seek to minimise the production of hazardous substance and their release to the environment

Question 9

Atom economy

Answer 9

Mr of desired product / total Mr of all reactants

x 100

the higher the % the more efficient the process