fuels

• The food you eat contains a fuel (carbohydrates) which don’t need to be combusted to release energy.  They are broken down in the body and respiration produces the energy.
• Crude oil is the main source of organic fuels; hydrocarbons.  It is called a fossil fuel as it was made millions of years ago by the breakdown of plant and animal remains.  It is a non-renewable resource as it takes such a long time to produce. 
• Alkanes are hydrocarbons that contain only carbon-carbon and carbon-hydrogen single bonds and can be represented by the general formula CnH2n+2, where n = number of carbon atoms present.
• Ethanol is a carbon neutral fuel, as the carbon dioxide (which is a greenhouse gas) produced when ethanol combusts can be used up by the plants during photosynthesis which are grown to produced the sugar needed to make the ethanol.
• The energy content of foods can also be investigated using a similar setup to practical’s we have previously seen. A measured mass of food is ignited and used to heat a known volume of water is heated and the temperature rise is recorded using a thermometer.