C7

• Hydrogen atom can make 1 bond each
• Carbon atoms can make 4 bonds each
• The simplest alkane is methane which is CH 4 which is one carbon with 4 hydrogen atoms
• Ethane

  C 2 H 6

  2 carbon atoms

  6 hydrogen atoms
• Propane

  C 3 H 8

  3 Carbon atoms

  8 hydrogen atoms
• Butane

  C 4 H 10

  4 carbon atoms

  10 hydrogen atoms
• Most of the compounds in crude oil are hydrocarbons
• the larger the hydrocarbon

  the more viscous

  The higher the boiling point

  less volatile

  Less easily it is to ignite
• Crude oil can separated into many different parts by fractional distillation
• Shorter hydrocarbon molecules can reach the top of a fraction column before they condense and are collected
• Longer hydrocarbon molecules condense at a higher temperature and are collected lower down the column
• Alkanes = singles bond

  Alkenes = double bond
• Alkanes are described as saturated hydrocarbons because they contain only single bonds between carbon atoms
• The formula for alkanes is

  C (n) H (2n+2)
• During combustion of hydrocarbon fuels

  both carbon and hydrogen are oxidised

  energy is released

  Waste products are produces which are released into the atmosphere
• hydrocarbon + oxygen ( burnt with limited oxygen) ----> carbon (soot) + carbon monoxide + carbon dioxide + water
• hydrocarbon + oxygen (burnt with oxygen) ---> carbon dioxide + water
• Long chain hydrocarbons can be broken down into shorter more useful hydrocarbons this process is called cracking
• During catalytic cracking

  the hydrocarbons are heated until they vaporise

  the vapour passed over a hot catalyst

  a thermal decomposition reaction takes places

  the products include alkanes an alkenes
• long chain alkane ---(heat + catalyst)---> short chain alkane + alkene
• There is a high demand for fuels with small chain hydrocarbons because they easily ignite and have low boiling points
• Alkenes can be used to make a range of new compounds, including polymers and industrial alcohol
• Not all the carbon atoms have to be linked to four other atoms as a double carbon - carbon bond can be present
• Hydrocarbons which have double bonds are described as unsaturated
• Formula for Alkenes

  C (n) H (2n)
• There are ethene (C2H4) , propene (C3H6) , butene (C4H8)
• Label the diagram

  A) ethane

  B) ethene

  
• Alkene are more reactive than alkanes due to the double carbon bond
• Alkenes burn with smokier flames due to the incomplete combustion
• Hydrogen can be added to alkenes to produce alkanes
• propene + hydrogen -----> propane

  this is called an additional reaction
• Ethene (colourless) + bromine water (orange / brown) ----> colourless solution

  Ethane (colourless) + bromine water (orange / brown) ----> remains orange / brown solution
• Aqueous solution of ethanol can be produced by fermentation of sugar
• Fermentation equation

  sugar ---> ethanol + carbo dioxide
• Alcohols are carbon based molecules that contain the function group hydroxyl (-OH)
• Methanol , ethanol , propanol and butanol are the first 4 members of the homologous series of alcohols
• Alcohols:

  dissolve in water to form a neutral solution

  react with sodium to produce hydrogen

  are used as fuels as solvents
• Carboxylic acid are organic compounds that contain the functional group carboxyl (-COOH)
• Carboxylic acids:

  Dissolve in water to form acidic solutions

  react with carbonates to produce carbon dioxide

  React with alcohol to form esters

  Do not ionise (dissociate) fully in water so they are called weak acids
• Alcohols and carboxylic acids react together to form esters