organic chemistry

• what is crude oil?

  -formed over millions of years from the fossilised remains of plankton

  -found in porous rocks in the earths crust

  -a finite resource that is used to produce fuels and other chemicals
• what are the majority of compounds in crude oil?

  hydrocarbons
• what is a hydrocarbon?

  molecules made only out of hydrogen and carbon atoms
• what is a hydrocarbon?

  molecules made only out of hydrogen and carbon atoms
• what is affected by hydrocarbons varying in size?

  -their properties

  -how they can be used as fuels
• what happens if the hydrocarbon is large?

  -flows (viscous) less easily

  -higher the boiling point

  -harder it is to ignite

  -less easily evaporated
• how can crude oil be separated?

  Fractional distillation
• what are most hydrocarbons obtained?

  alkanes
• what is the process of fractional distillation of hydrocarbons?

  -crude oil is heated until it evaporates

  -vapour moves up the fractional column

  -the top of the column is much cooler than the bottom

  -shorter hydrocarbon molecules reach the top before they condense and are collected higher up the column

  -longer hydrocarbon molecules condense at higher temperatures and are collected lower down the column
• what part of the fractional distillation column is hottest?

  Bottom
• what part of the fractional distillation column is coldest?

  Top
• what are alkanes?


  -contain only single bonds

  -described as saturated hydrocarbons (they contain the maximum number of bonds possible)

  -fairly unreactive but burn well
• what are fuels?

  Substances that can be burned to release energy
• what is the formula for alkanes?

  CnH2n+2
• what type of alkanes release energy quicker?

  Shorter-chain alkanes
• why is there a higher demand for shorter-chain alkanes?

  They release more energy quicker (by burning), so there is a greater demand for them as fuels. They also have low boiling points and are easy to ignite
• what is the simplest alkane?

  methane
• what is methane made up of?

  4 hydrogen atoms 1 carbon atom
• what is methane made up of?

  4 hydrogen atoms 1 carbon atom
• what is ethane made up of?

  2 carbon atoms 6 hydrogen atoms
• what is propane made up of?

  3 carbon atoms 8 hydrogen atoms
• what is butane made up of?

  4 carbon atoms 10 hydrogen atoms
• what happens during the combustion of hydrocarbons?

  -both carbon and hydrogen are oxidised

  -energy is released

  -waste products are produced and released into the atmosphere
• what is carbon monoxide?

  -colourless

  -produced in incomplete combustion

  -odourless

  -toxic gas
• what is produced in incomplete combustion?

  -carbon monoxide

  -unburnt fuels

  -solid particles containing soot
• why is the release of solid particles bad?

  Solid particles in the air (particulates) can cause global dimming by reducing the amount of sunlight reaching Earths surface and cause damage to peoples lungs
• why is nitrogen oxide formed when fuel is burned?

  Due to the high temperatures reached , nitrogen in the air can react with oxygen to form nitrogen oxide
• why is the production of nitrogen oxide bad?

  These gases can cause respiratory problems in people and react with rain water to from acid rain which can damage plants and buildings
• what is cracking?

  Breaking down long-chain hydrocarbons into useful short-chain alkanes and reactive alkene molecules
• what are the 2 main methods of cracking?

  -steam cracking

  -catalytic cracking
• what happens in steam cracking?

  -the hydrocarbons are mixed with steam

  -they are heated to 850 degrees
• what happens in catalytic cracking?


  -the hydrocarbons are heated until they vaporise

  -the vapour is passed over a hot aluminium oxide catalyst

  -a thermal decomposition reactions takes place
• what are the products of cracking a hyrdocarbon?

  -alkanes

  -alkenes
• what are the alkenes from cracking hydrocarbons used for?


  make a range of new compounds, including polymers and industrial alcohol
• what is more reactive than alkanes?

  alkenes
• how do alkenes react with bromine water?

  When shaken they turn the water orange to colourless
• what does bromine water allow us to do?

  differentiate between alkanes and alkenes
• crude oil is found in rocks and is a finite resource
• crude oil is formed over millions of years from the remains of tiny sea creatures called plankton which were buried in mud
• crude oil is a mixture of molecules called hydrocarbons