Fuel choices Flashcards
Define fuel
a fuel is a substance that can be reacted with other substances (often oxygen) leading to the release of energy (usually chemical) that can be harnessed for a specific purpose
Define renewablility
A renewable fuel is one that can be replenished or replaced by natural processes within a related short period of time renewable feels like considered a substantial source of fuel, since we can continually replenish the fuel.
Define fossil fuel
Fossil fuels are chemicals that are produced by fossilization of dead plants and animals
Fossilisation process in the formation of fuels
Occurs over millions of years, the preserved dead organism is subject to high pressures in the multiple layers of rock and sentiment that formed over it, and the chemicals are comprise the organism are broken down into a mixture of hydrocarbons and other organic substances. This leads to the formation of a mixture of solid coal, liquid crude oil and natural gases
Fossil fuels are considered…
a non renewable source of energy this is because the rate of which fossil fuel production by fossilisation occurs is extremely slow
Define biofuels
Are fuels that are derived from matter from living or recently deceased plants
Process of biofuels
Photosynthesis is the process by which plants produce glucose from C2O and H2O using sunlight as a source of energy. The glucose is converted into other organic molecules such as oils protein and complex carbohydrates, these organic molecules including glucose and oils can be extracted and the plant and chemically modified to form biofuels such as bioethanol and biodiesel
When is biogas produced
Biogas is produced when plants die and start to decompose, bacteria breaks down these large molecules into smaller molecules including methane gas, these fuels are renewable.
How are biofuels carbon neutral (no net production of CO2)
CO2 released during the burning of fuel is approximately equal to the CO2 consumed during the production of the fuel example growing of the crops (via photosynthesis)
Biofuel
Burning of fuels
Fuels that burn in oxygen are combustion reactions. Combustion reactions are exothermic reactions (ie ΔH<0) Where there is a net loss release of chemical energy throughout the reaction. Chemical energy is converted into other forms of energy such as thermal energy light energy and in some cases mechanical energy
Biofuel
Burning of fuels
1 MJ = ____ kJ and 1 tonne = _____ kg
1000, 1000
Biofuel
Define complete combustion
Complete combustion occurs when a fuel is burnt in excessive oxygen to form CO2 and H2O
Biofuel
Define incomplete combustion
Incomplete combustion occurs when a fuel is burnt in limited amount of oxygen this produces CO
Biofuel
The enthalpy of incomplete combustion of a fuel is always ____ negative than the enthalpy of complete combustion of a fuel
Less
Biofuel
Greenhouse gases
The thing about fuels is that when you combust them, you produce greenhouse gases which are gases that can absorb infrared radiation which warms up the planet. Greenhouse gases include CO2 and Ch4 as well as water vapour H2O. Excess production of greenhouse gases is problematic because they can cause global warming also known as climate change
Fossil fuel choices
Define coal
a black rock, is a fossil fuel that is composed of a variety of very long hydrocarbon molecules that, like any other hydrocarbon, can be combusted to release energy to generate electricity. The energy content of coal is approximately 30 MJ / kg. -Non renewable
Fossil fuel choices
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- Wildlife habitat is destroyed
- contamination of water within underground water disposits
- Coal miners who breathe coal dust can end up getting black lung disease
Fossil fuel choices
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-Combustion of coal leads to the production of greenhouse gas CO2, which to contributes to global warming
- Coal is a mixture of N and S atoms (+ others) therefore the production leads to NO and NO2.
Therefore the Nitrogen and sulphur oxides, being acidic acid can react with and dissolve in water to form acid rain
-The burning coal also leads to release of particular matter in air which is basically unburnt bits of coal this contributes to air pollution and smog and when inhaled can cause serious health effects
Fossil fuel choices
Define crude oil
a black tarry liquid that is composed of a series of large hydrocarbon molecules and other organic molecules containing some N and S atoms
Fossil fuel choices
Crude oils The products of fractional distillation are -L -P -K -D -F
- Liquidfied petroleum gas (LPG): a mixture of propane and butane
- Petrol: liquids containing about 8-10 carbons
- Kerosene: slightly more viscous liquids, used as jet fuel
- Diesel: more viscous liquid containing (15 carbon atoms)
- Fuel oil: mixture of large hydrocarbon atoms, a black tarry liquid
Fossil fuel choices
Process of crude oil
Crude oil is very rarely used in its raw form as a fuel. It is first refined (the different compound of crude oil are separated by fractional diffusion (The components are separated by boiling point and therefore by molecular size)