Green chemistry

Question 1

Fossil fuel

Answer 1

A mixture of hydrocarbons laid down over millions of years through the anaerobic decay of animal and vegetation matter, used as a fuel that releases carbon dioxide when combusted

Question 2

Biofuel

Answer 2

Fuel made from renewable organic materials like sugar, grain or vegetable oils

Question 3

Carbon footprint

Answer 3

A measure of the impact human activities have on the environment in terms of amount of carbon dioxide produced. Measured in tonnes of carbon dioxide per event.

Question 4

Transesterification

Answer 4

A reaction between an ester and an alcohol that produces a different ester and a different alcohol

Question 5

Atom economy (with equation)

Answer 5

The % of atoms in the reactants present in the desired product: mass of atoms in desired product/ mass of atoms in reactants x 100%

Question 6

Biodegradable

Answer 6

Bacteria cause the decomposition of the organic material to carbon dioxide or methane and water

Question 7

Photolysis

Answer 7

The breaking of a bond by light

Question 8

Ozone/oxygen reactions in the ozone layer

Answer 8

O3 (+ 200-300nm UV) -> O2 + O.
O2 (+ 180-240nm UV) -> O. + O.
O. + O2 -> O3 (delta H = -600 kJ mol-1)

Question 9

CFC reactions in the ozone layer

Answer 9

CF2Cl2 (+UV) -> CF2Cl. + Cl.
Cl. + O3 -> ClO. + O2
ClO. + O. -> Cl. + O2
So overall: 2O3 -> 3O2

Question 10

Nitric oxide reactions in the ozone layer

Answer 10

NO + O3 -> NO2 + O2
NO2 + O. -> O2 + NO
So overall: 2O3 -> 3O2

Question 11

Free radical

Answer 11

An uncharged species with an unpaired electron that is used to form a covalent bond - highly reactive

Question 12

Green chemistry

Answer 12

The utilisation of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products

Question 13

Relative greenhouse factor of a gas

Answer 13

Compares the effects that different gases have in absorbing infrared radiation compared with carbon dioxide

Question 14

Global warming potential (GWP)

Answer 14

Determined by their relative greenhouse factor and their half-life in the atmosphere

Question 15

Carbon neutral (fuel)

Answer 15

When the amount of carbon dioxide absorbed when the raw material is grown, or the fuel is formed, equals the amount of carbon dioxide produced when it is manufactured and burnt

Question 16

Biodispersible

Answer 16

Organisms cause the plastic to crumble and become dispersed in the environment

Question 17

Equation for sulphur dioxide removal from flue gases

Answer 17

2CaCO3 (s) + 2SO (g) + O2 (g) -> 2CaSO4 (s) + 2CO2 (g)