Organic chemistry

• hydrocarbons

  any compound that is formed from carbon and hydrogen atoms only
• Alkanes - all C-C single bonds

  general formula: CnH2n+2; Alkanes are a homologous series- a group of organic compounds that react in similar way; Alkanes are saturated compounds - each carbon atom forms 4 single covalent bonds; examples are methane, ethane, propane, butane
• complete combustion- occurs with the presence of oxygen


  the complete combustion of any hydrocarbon in oxygen releases a lot of energy; the only waste products are carbon dioxide and water vapour; During combustion, both carbon and hydrogen from the hydrocarbon are oxidised; hydrocarbons are used as fuels due to the amount of energy released when they are combust completely
• balanced symbol equation for complete combustion

  CH4 + 2O2 -> CO2 + 2H2O
• crude oil

  a fossil fuel; formed from the remains of plants and animals (mainly plankton), that died millions of years ago and were buried in mud; Over millions of years, with high temperature and pressure, the remains turn into crude oil which can be drilled and collected from rocks
• fractional distillation

  oil is heated until most has turned into gas; the gas enters a (fractionating) column; in the column there's a temperature gradient - cooler as you go up; the longer hydrocarbons have high boiling points; they condense back into liquids and drain out of the column first; shorter hydrocarbons have a lower boiling point so they condense and drain last; each fraction contains a mixture of hydrocarbons that contain the similar number of carbon atoms with similar properties
• cracking

  splitting up long-chain hydrocarbons
• A pure substance only contains one compound or element throughout - not mixed with anything else
• Boiling points or melting points in pure substances

  A chemically pure substance will melt or boil at a specific temperature
• Formulations

  Formulations are useful mixtures with exact amounts of components; Each component in a formulation is present in a measured quantity, and contributes to the properties of the formulation so that it meets its required function
• paints are formulations composed of: Pigment - gives the paint colour; Solvent - used to dissolve the components and alter the viscosity; binder (resin) - forms a film that holds the pigment in place after its been painted on; Additives - added to further change the physical and chemical properties of the paint
• Chromatography

  An analytical method used to separate the substances in a mixture
• mobile phase

  Where the molecules can move. This is always in a liquid or gas
• stationary phase

  Where the molecules can't move. This can be a solid or a really thick liquid
• Test for gases: Chlorine

  Chlorine bleaches damp litmus paper, turning it white
• Test for gases: Oxygen


  If you put a glowing splint inside a test tube containing oxygen, the oxygen will relight the glowing splint
• Test for gases: Carbon Dioxide

  Bubbling carbon dioxide through an aqueous solution of calcium hydroxide or limewater causes the solution to turn cloudy
• Test for gases: Hydrogen


  If you hold a lit splint at the open end of a test tube containing hydrogen, you'll get a "squeaky pop". (The noise comes from hydrogen burning quickly with oxygen in the air to form water)