Resources Flashcards
Infrared radiation is absorbed by…
C=O, O-H and C-H bonds in H2O, CO2 and CH4
These absorptions contribute to global warming
What is the ‘Greenhouse Effect’ of a given gas dependent on?
Its atmospheric concentration and its ability to absorb infrared radiation
How are chemists trying to minimise climate change?
Using carbon capture and storage - eg injecting liquid CO2 deep in the oceans, storage on deep geological formations
Turning CO2 into stable carbonates by reacting with metal oxides
Educating society
Providing scientific evidence to governments
Monitoring atmospheric changes
What are some effects of climate change?
Rivers overflowing due to heavy rainfall and melting glaciers
In other areas, drought-like conditions lead to water shortages
In some regions, longer growing seasons improve crop yields, whereas others experience drought and disease
How is the concentration of ozone is maintained in the ozone layer?
The reaction O2 + O –> O3 is reversible. The rate of the forward reaction equals the rate of the reverse reaction
Why is ozone essential for life on earth?
It absorbs harmful UV radiation which can cause skin cancers
Describe how CFCs can catalyse the breakdown of ozone
Cl• (from CFC) + O3 –> ClO• + O2
ClO• + O –> Cl• + O2
Overall reaction: O3 + O –> 2O2
Describe how NO2 can catalyse the breakdown of ozone
NO• + O3 –> •NO2 + O2
•NO2 + O –> NO• + O2
Overall reaction: O3 + O –> 2O2
Where does NO2 from the atmosphere come from?
Thunderstorms or aircrafts
How can oxides of nitrogen be formed and why are they a problem?
Nitrogen monoxide and nitrogen dioxide are formed in the internal combustion engine, as nitrogen from the air is oxidised by the oxygen
NO2 contributes to the formation of low-level ozone, and can be converted into nitric acid, a contributor to acid rain
Nitrogen oxides are respiratory irritants
How are inburnt hydrocarbons formed and why are they a problem?
They are released in vehicle exhaust gases
They are known to be human carcinogens
They can react with nitrogen dioxide to form low-level ozone
Why is low-level ozone a problem?
The energy for the reaction that forms low-level ozone is sunlight
It causes breathing difficulties and increased susceptibility to infections
Outline how a catalytic converter works
The catalyst provides a surface on which the reaction takes place
CO and NO molecules are adsorbed onto the surface
The bonds between the atoms are weakened, and so the activation energy is lowered
The reaction happens: 2CO + 2NO –> 2CO2 + N2
CO2 and N2 are desorbed from the surface
Give 5 ways in which reactions can be made more sustainable
1) using industrial processes that reduce or eliminate hazardous chemicals and which involve the use of fewer chemicals
2) designing processes with a high atom economy that minimise the production of waste materials
3) using renewable resources such as plant-based substances
4) seeking alternative energy sources such as solar energy, rather than consuming finite resources such as fossil fuels that will eventually be exhausted
5) ensuring that any waste products are non-toxic, and can be recycled or biodegraded by being broken down into harmless substances in the environment
How can carbon monoxide be formed and why is it a problem?
It can be formed from the internal combustion engine in cars by the incomplete combustion of hydrocarbons and other organic products
It is a toxic gas
