Fuels!!! Flashcards
All about the fuelllllls
What is a fuel?
a substance that burns in air or oxygen to release a USABLE amount of energy
What are the 5 types of Fossil fuels?
- Methane
- Octane
- Coal Seam gas (CSG)
- Liquid petroleum gas (LPG)
- Diesel/petrodiesel
What are the 3 types of Biofuels?
- Biogas
- Bioethanol
- Biodiesel
What are the 3 fuels of the body?
- Carbohydrates
- Lipids (Fats and oils)
- Proteins
What is heat of combustion?
the heat energy release when a specific amount of fuel burns completely in oxygen. It’s thus reported as a positive value (indicating a magnitude)
What are the 2 parts for a THERMOchemical equation?
- Balanced equation
- Enthalpy change (triangleH= + for endothermic/ - for exothermic)
How do you find the energy content per gram?
energy content/g = triangleH / molar mass
How do you find the energy content from mol of fuel?
q = n x (triangleH / coefficient for fuel)
For Q=m x c x change in T, what can it only be used for?
water (as c is the specific heat capacity of water)
What is a non-renewable resource?
One that is NOT able to be replenished at a rate greater than or equal to the rate it is being consumed / used
What is a renewable resource?
One that can be replenished at a rate as quickly or faster than the rate they are being consumed / used
What is Transesterification?
A chemical reaction used to produce biodiesel and glycerol
What are examples of non-renewable fuels? (7)
- Methane
- Natural gas (primarily methane)
- Butane
- Octane
- Coal
- Coal-seam gas (CSG)
- Diesel/Petrodiesel
What are examples of renewable fuels (and their sources)?
- Biogas (fermentation of waste products/plant materials)
- Bioethanol (fermentation of glucose)
- Biodiesel (is from methyl esters/ fatty acid + methanol reaction)
What is the main advantages of using biofuels?
- they are renewable
- they are largely carbon-neutral
What are some advantages of using biogas?
- Renewable
- Almost net zero release of atmospheric carbon dioxide because carbon dioxide is absorbed by the plants during photosynthesis
- Produced from waste
- Reduces waste disposal
- Low running costs
- zero sulfur emissions
- Burns / combusts more completely
What are some disadvantages of using biogas?
- Less energy dense compared to fossil fuel alternatives
- Supply of waste raw materials is limited hygroscopic (absorbs water)
What are some advantages of using bioethanol?
- Renewable
- Almost net zero release of atmospheric carbon dioxide because carbon dioxide is absorbed by the plants during photosynthesis
- can be made from waste
- Burns smoothly
- Fewer particulates produced compared to petrol
What are some disadvantages of using bioethanol?
- Limited supply of raw materials from which to produce it
- Lower energy content than petrol
- May require use of farmland otherwise used for food production
What are some advantages of using coal as a fuel?
- Large reserves
- Relatively high energy content
What are some disadvantages of using coal as a fuel?
- Non-renewable
- Increases atmospheric carbon dioxide levels
- Less easily transported than liquid or gaseous fuel (as cannot be transported in pipes)
- Releases sulfur based pollution into the atmosphere
What are some advantages of using natural gas as a fuel?
- Relatively high energy content
- More efficient than coal for electricity production
- Easy to transport through pipes
What are some disadvantages of using natural gas as a fuel?
- Non-renewable
- Limited reserves
- Releases greenhouse gases such as CO2 (but less compared to coal and petrol)
What are some advantages of using petrol / petrodiesel as a fuel?
- High energy content
- Ease of transport
What are some disadvantages of using petrol / petrodiesel as a fuel
- Non-renewable
- Increases atmospheric carbon dioxide levels
- Polluting, but less than coal
How is biodiesel formed?
- Esterification of fats and oils in organic matter (animal products and oils originating from crops).
- Biodiesel is formed form a reaction between a fatty acid with an alkanol
How is biogas produced?
- Biogas is produced from the anaerobic breakdown of biomass / organic matter by bacteria.
- Examples of biomass include algae, crops, wood, compostable garbage.
How is bioethanol produced?
- By the fermentation of glucose in organic matter by a microorganism called yeast.
- Example of organic matter include crops such as wheat, corn and sugarcane.
What is the main functional group in biodiesel and what is it commonly called?
- ester (group)
- methyl ester
What is the chemical and word equation for photosynthesis?
- carbon dioxide + water -> glucose + oxygen
- 6CO2 + 6H2O -> C6H12O6 + 6O2
What is the chemical and word equation for fermentation of ethanol (in yeast)
- Glucose –(bacteria)—-> Ethanol + Carbon dioxide
- C6H12O6 (aq) —(bacteria)—->2CH3CH2OH(l) + 2CO2(g)
What is the word equation for transesterification?
its for biodiesel
triglyceride + 3 methanol -> 3 methyl esters (biodiesel) + glycerol
State if fuels generally have a high or low boiling point, flashpoint, flammability
Fuels generally have low boiling point, low flashpoint, high flammability
Compare the properties of biodiesel versus petrodiesel.
- biodiesel has higher viscosity than petrodiesel
- biodiesel has higher freezing point than petrodiesel
- biodiesel has higher viscosity particularly at cold -temperatures
- biodiesel is more hygroscopic than petrodiesel
- biodiesel has higher melting point than petrodiesel
- biodiesel is less energy dense than petrodiesel
- biodiesel forms a gel / crystalises at a higher temperature (resulting in increased viscosity and poor flow at lower temps)
- biodiesel cloudpoint is higher than petrodiesel
- biodiesel is more likely to oxidise causing a gum-like substance to form in the fuel.
Compare the production of biodiesel versus petrodiesel.
- Biodiesel is produced from biomass / organic matter which is a renewable energy source where as petrodiesel is produced from fossil fuels which as non-renewable.
- Biodiesel requires land and water to produce. This land / water could otherwise be used for food production.
- Petrodiesel requires drilling of crude oil. Oil fields / refineries are prone to oil spills and produce emissions that have a negative affect on the environment.
Compare the environmental affect of biodiesel versus petrodiesel.
- BIOdiesel produces a lower (almost net zero) net emission of carbon dioxide due to partial offset from the absorption of CO2 whist growing whereas PETROdiesel has a greater net emission of carbon dioxide into the atmosphere
- Biodiesel produces fewer particulates and fewer pollutants compared to petrodiesel.
What is activation energy?
the minimum amount of energy required for a reaction to proceed
What is the difference between incomplete and complete combustion?
- incomplete = produces CO or C
- complete = produces CO2
What is metabolism?
All the chemical reactions in the body’s cells that change food into energy
What is calorimetry?
method of measuring the heat energy released or absorbed by a chemical reaction/physical process.
eg. combustion of food or a fuel
What are Calorimeters?
The name of the devices that measure the energy changes by using heat
(more accurate tool for measuring energy content of foods)
What is a Bomb calorimeters?
used to measure the heat of combustion of chemical reactions involving gaseous reactants/products
note heat of combustion = amount of heat released by the complete combustion of a substance eg fuels
What are the types of reactions and uses for bomb calorimeters?
- Reactions = ALWAYS exothermic b/c COMBUSTION
- Uses = measuring heat content of food or fuels
What are some features of bomb calorimeter? (6)
- withstands high pressures and temperature whilst maintaining a constant volume
- wired electrical current -> electrically ignite to start combustion
- sufficient oxygen required
- surrounded by vessel of H2O
- Insulations to prevent heat being release into outside environment
- stirrer heat evenly distributed
What is solution calorimetry?
it calculates the energy transferred in a chemical reaction with a simpler instrument
What are the types of reactions and uses of solution calorimeters?
- Reactions = sometimes exothermic or sometimes endothermic
- Uses = measuring of heat of solution, neutralisation or of any other reaction that occurs in the solution
What are some features of solution calorimeter?
- made with polystyrene cup at constant pressure
- contains known H2O volume
- Exothermic if increase temp of water and Endothermic if decrease temp of water
LIMITATIONS: - cup does absorb some heat from H2O thus temp change slightly less than true value
- cannot measure energy content of food (combustion X occur in aqueous solution
What are some issues (random errors) that can arise with calorimeters?
- not all food/substance combusted
- incomplete combustion of food -> lower energy content
- temperature recorded when food combusted inaccurate
What are some issues (systematic errors) that can arise with calorimeters?
- poorly insulated
- calibration done incorrectly
- measurements utilised to calibrate were measured incorrectly
Explain why biofuels produced from plants are considered to be almost carbon neutral / have approximately zero net impact on atmospheric carbon dioxide.
- Because plants undergo photosynthesis whilst they grow, they absorb carbon dioxide from the atmosphere
- Then when the plant is converted into a biofuel and burned, the carbon dioxide absorbed by the plant is released back into the atmosphere
- Therefore there is not NET release of carbon dioxide in to the atmosphere
State some storage considerations for a fuel
- store away from naked flames (because fuels are flammable)
- store in well ventilate areas (to avoid suffocation / asphyxiation)
Describe the greenhouse effect
the process of the warming of the Earths lower atmosphere due to the increased quantities of gases of ‘greenhouse gases’ such as carbon dioxide, water vapour and methane in the air
What is petrodiesel?
A liquid hydrocarbon fossil fuel obtained from crude oil
