Green Chemistry

Question 1

Factors for choosing chemicals

Answer 1

1. Cost
2. Concentration of chemicals
3. Toxicity of raw materials
4. Flammability
5. Volatility

Question 2

High atom economy=?

Answer 2

More useful products / less waste

Question 3

How does catalyst provide economic and environmental benefits? (3 marks)

Answer 3

Lower temperatures can be used (1)
Energy costs saved (1)
More product can be made in a given time (so more can be sold)
(1) Enable reactions to take place that would be impossible
otherwise (1)
Less fossil fuels burned to provide energy (so less CO2 formed)

Question 4

Effects of acid rain (2 marks)

Answer 4

1. Damaging marble statues

2. Killing marine lives/trees

Question 5

Justify if methane or charcoal is a better fuel. (9 marks)

Answer 5

Correct in that energy produced per gram is 32.8 kJ from charcoal and 55.6 kJ from methane
Both give CO2 on burning
1 mol of each fuel produces 1 mol of CO2
Wood for charcoal comes from (living) trees
Methane comes from sources living millions of years ago / is a fossil fuel
Charcoal is renewable / methane is non-renewable
Trees take in CO2 in photosynthesis
Trees release the same amount of CO2 on combustion that they took in during growth
Charcoal burning is overall carbon neutral

Question 6

Why is HFCs more preferred to CFCs? (5 marks)

Answer 6

CFCs destroy ozone
we are then more exposed to UV radiation / greater risk of skin cancer
(CFCs) produce ·Cl / chlorine radical / HFCs do not produce ·Cl
·Cl / chlorine radical starts chain reaction
HFCs contain C—H / C—F bonds and these are too strong to be broken by UV light

Question 7

Suggest other sources of electricity that are sustainable. (5 marks)

Answer 7

Wind / hydro / biomass / solar / geothermal (1)
Rotation of blades turns turbine / falling water turns turbine / combustion steam turns turbine / sunlight on photovoltaic cell produces electricity (1)

Question 8

Catalytic converters used in ?

Catalyst used?

Answer 8

Exhaust

Platinum

Question 9

Explain the negative impact of burning CFCs. (4 marks)

Answer 9

C-Cl bond can be broken down by UV light to produce chlorine radicals / Cl· (1)
these destroy the ozone layer (1)
the ozone layer protects us from UV radiation (1)
UV radiation causes (skin) cancer / mutations (1)