8: Fuels and Earth science

acid rain

rain that is acidic due to gases such as sulphur dioxide reacting with water vapour in the clouds. sulphur dioxide is produced from the burning of fossil fuels which contain sulphur impurites

alkanes

the most common hydrocarbon found in crude oil. they have the formula C n H 2n + 2

alkenes

alkenes are hydrocarbons with a double bond between 2 of the carbon atoms in their chain, causing them to be unsaturated. they have the general formula C n H 2n

catalytic cracking

long-chain hydrocarbons are heated to turn them into a gas. the vapour is then passed over a hot powdered aluminium oxide catalyst. the long chain molecules split apart on the surface of the catylist

climate change

a change in global climate patterns largely believed to be caused by the increase in concentration of CO2 in the atmosphere

combustion

the burning of a substance in oxygen causing energy to be transferred to the surroundings as heat and light. during this process, the carbon and the hydrogen in the fuels are oxidised

complete combustion

combustion carried out in sufficient oxygen. Water and carbon dioxide are the only products in the complete combustion of hydrocarbons

cracking

a process that involves breaking down larger hydrocarbons to produce smaller, more useful molecules

crude oil

a finite resource found in rocks. it is the remains of an ancient biomass consisting mainly of plankton that were buried in the mud. most of the compounds in crude oil are hydrocarbons

finite resource

a resource that will run out

fossil fuel

natural fuels, such as coal and gas, formed in the past remains of living organisms

fractional distillation

a process used to separate a mixture of liquids using a fractionating coulmn

general formula

a chemical formula that applies to a class of compounds, representing the composition of the atoms present

greenhouse effect

the increase in temperature of the Earth’s atmosphere due to the greenhouse gases in the atmosphere trapping infra-red radiation from the surface

greenhouse gasses

gases in the atmosphere which maintain temperatures on Earth high enough to support life

homologous series

a series of compounds with the same functional group and similar chemical properties

hydrocarbons

molecules that are made up of hydrogen and carbon atoms only

incomplete combustion

combustion which is carried out with insufficient oxygen. it can lead to the production of toxic carbon monoxide and carbon particles

non-renewable energy

an energy resource which is finite

particulates

polluting particles which cause global dimming and health problems for humans

photosynthesis

a reaction which occurs in plants and algae which led to the production of oxygen and the reduction of CO2 in the early atmosphere

pollutants

a substance introduced into the environment that has undesired effects

steam cracking

long-chain hydrocarbons are heated to turn them into a gas. the hydrocarbon vapour is the mixed with steam and heated to a very high temperature which causes them to split into smaller molecules

chemical test for chlorine

damp litmus paper is bleached by chlorine gas