2.3- The Wider Impact of Chemistry Flashcards
(17 cards)
(a)
Chemical synthesis
Chemical synthesis is the process of carrying out specific chemical reactions in order to produce a desired compound.
(a)
Sustainable chemistry
Sustainable chemistry is chemistry that is carried out with the intention to not use up the earth’s resources and to limit the amount of pollutants released.
(a)
What should be considered when choosing a reaction pathway to synthesise a desired product?
Availability of reactants.
Least waste produced (high atom economy).
Fewest stages possible.
Fastest rate of reaction.
Safe reaction conditions.
(a)
How does atom economy relate to sustainable chemistry?
The higher the atom economy, the more sustainable the reaction is. This is because there is less waste being produced.
(a)
economic impacts of chemical synthesis
- The chemical synthesis process provides jobs for people involved in the production.
- There is a demand for the chemical being produced, like medicine, so the product will generally be economically valuable.
(a)
social impacts of chemical synthesis
Chemical synthesis allows for important products like drugs and polymers to be produced which help people in everyday life.
(a)
environmental impacts of chemical synthesis
Choose the synthesis route with the lowest environmental impact:
* Use renewable reactants – more sustainable
* Pick route with high atom economy and low waste
* Avoid fast reactions that make lots of pollutants
* Choose conditions needing less energy – cuts down pollution
(a)
Explain the environmental effects of energy production
Energy is often produced by burning fossil fuels, which are finite and unsustainable. Burning them releases harmful gases like carbon dioxide, which contribute to global warming.
Renewable sources (e.g. solar, tidal) are sustainable and don’t release harmful gases, but they are less commonly used.
(a)
Catalytic converter
A catalytic converter is fitted in a car to convert the harmful carbon monoxide (CO) and oxides of nitrogen (NOX ) emissions to less harmful carbon dioxide (CO2 ) and nitrogen (N2 )
(a)
chemical equation for the reaction that takes place in a catalytic converter
2CO + 2NO → 2CO2+ N2
(a)
production of acid rain
Sulfur dioxide gas (produced during the combustion of impure hydrocarbon fuels) is released into the air. It reacts with water in the clouds to form sulfuric acid. This falls as ‘acid rain’.
(a)
environmental impacts of acid rain
- Corrodes buildings and statues made of limestone.
- Kills vegetation.
- Lowers the pH of large bodies of water, killing the wildlife.
(a)
‘carbon neutral’ fuel
A fuel is carbon neutral if it contributes to no net increase of carbon dioxide levels in the atmosphere.
(a)
Advantage and disadvantage of hydrogen
Advantage- clean only produces water when burnt
Disadvantage- doesn’t occur naturally on earth. Expensive and difficult to produce (uses fossil fuels for energy)
(b)
key principles of green chemistry
Conditions of the reaction - higher temperature or higher pressure means more energy is needed (environmentally bad)
Environmentally friendly starting materials (e.g. are they made from plants - good or fossil fuels - bad)
(b)
key principles of green chemistry (2)
Hazardous By-products
CO2 - green house gas, contributes to global warming.
NOx and SOx - acid rain.
SOx formed by burning sulfur (majority from coal)
NO, formed by combustion of atmospheric nitrogen (needs high temperatures - e.g. in car engine)
Anything that needs to be separated means more money and time
(b)
CFC’s versus HFC’s
CFC’s destroy the ozone layer. The ozone layer protects from exposure to UV radiation- destructions means greater risk of skin cancer. CFCs produce a chlorine radical. Chlorine radical starts a chain reaction with ozone.
HFCs contain C-H and C-F bonds which are too strong to be broken by UV light so do not damage the ozone layer in the same way.
