Fuels Flashcards
What is petrol comprised of?
- A mix of alkane hydrocarbons
What is natural gas comprised of?
- Methane, followed by ethane, propane…
Where is natural gas found?
- Found in coal and petroleum deposits
How is bioethanol produced?
- Via anaerobic fermentation
- Needs to be separated from fermented solution using distillation
Why does bioethanol need to be separated from its fermented solution?
- If aqueous, water needs to be separated from the bioethanol
- Removing water increases energy content.
How is biogas made?
- Released in breakdown of organic matter by anaerobic bacteria
What is biodiesel comprised of?
- Mixture of esters
How is biodiesel produced?
- Produced between fats + oils and alcohol via transesterification
Advantages of coal
- Large reserves
- Easy transport
- High energy content
Disadvantages of Coal
- High emissions
- Non-Renewable
Advantages of Natural Gas
- More efficient than coal
- High energy content
Disadvantages of Natural Gas
- Limited reserves
- Polluting (less than coal and petrol)
Advantages of biogas
- Made from waste
- Low cost
- CO2 absorbed (photosynthesis)
Disadvantages of Biogas
- Low energy content
- Supply of raw materials is limited
Advantages of Petrol
- High energy content
- Easy transport
Disadvantages of Petrol
- Polluting (Less than coal)
- Limited reserves
Advantages of Bioethanol
- Can be made from waste
- CO2 absorbed (photosynthesis)
- Burns smoothly
Disadvantages of Bioethanol
- Limited supply
- Lower energy content than petrol
- May require farmland which would otherwise be used for food
Is photosynthesis an endo or exothermic reaction
- Endothermic
Is cellular respiration an endo or exothermic reaction?
- Exothermic
Is direct combustion efficient in comparison to direct conversion of energy?
Why?
- Direct combustion, i.e. car or power station, is less efficient
- There are more steps in this process where energy can be lost
- More energy is lost due to transformations required
(think of all the different mechanisms the energy needs to pass through… each loses energy)
Is the direct conversion of energy efficient in comparison to direct combustion?
Why?
- Chemical to electrical energy conversion, i.e. fuel cells (do not require combustion)
are more efficient - There are less steps in this process, meaning less energy is lost due to less transformations required.
Why does 2-methylpropan-1-ol have a lower energy content value than octane?
- 2-methylpropan-1-ol is partially oxidised
How does energy differ in incomplete combustion, in comparison to complete combustion?
- The energy of the products would be higher in incomplete combustion in comparison to complete, but still below reactants
- This is due to incomplete oxidisation of reactants
In combustion, partially oxidised compounds release…
… less energy than compounds not partially oxidised
