2.3 Green Chemistry Flashcards
What is the greenhouse effect?
- occurs when greenhouse gases in a planet’s atmosphere trap some of the heat radiated from the planet’s surface, raising its temperature
- contributes to climate change and global warming
Name some greenhouse gases
- water vapour
- carbon dioxide
- methane
- CFCs and nitrous oxides
How do greenhouse gases become harmful?
- specific bonds within substances absorb IR radiation causing molecules to vibrate and emit energy as radiation
Origins and impact of sulphur dioxide
- combustion of fossil fuels
- forms acid rain
Origins and impact of carbon monoxide
- incomplete combustion of hydrocarbons
- toxic as impacts O2 transport around body
Origins and impact of nitrogen oxides
- car engines
- acid rain and respiratory irritant
What are storage options for CO2 produces?
- inject deep underground where converted to liquid and stored in porous rock, ie geological formations and empty oil fields
- react CO2 with stable minerals to from carbonate (v energy intensive)
—> carbon capture storage
What is shale gas and what impact can collecting it have?
- produced by fracking which is used in power stations to make electricity
- subsidence, collapsed grounds, water contamination
Name low carbon energy and give some pros/cons
- wind: destroy landscape, noise pollution
- solar: takes up farm land, eyesore
- HEP: disrupts aquatic habitats
- nuclear: radioactive waste, terrorist threat, funding storage, huge structures
—> lots are v expensive and manufacturing process itself can be damaging
Explain the use of biodiesel in cars
- slightly less efficient than current fuel and produces lots of smog
- produced from oil extracted from plants
- replace or added to diesel
- classed as carbon neutral and less exhaust pollution
- crops and farmland used for fuel instead of food
Outline hydrogen fuel
- electrolysis of water
- produce v explosive hydrogen gas
- water contamination?
Methanol fuel cells are in development. What are pros and cons of this over hydrogen fuel?
Pros: liquid fuel easier to transport than gas, methanol from biomass is renewable
Cons: storing and transporting hydrogen, limited life, high production cost, use of toxic chemicals in production
What is a heterogeneous catalyst?
Catalyst that has different physical state to its reactants
What is a homogenous catalyst?
Catalyst which has the same physical state to its reactants
What is a catalytic converter? How does it work?
- a device used to reduce the emissions from an internal combustion engine
- used in exhaust systems to provide a site for the oxidation and reduction of toxic by-products (like nitrogen oxides, carbon monoxide, and hydrocarbons) of fuel into less hazardous substances such as carbon dioxide, water vapor, and nitrogen gas.
