C7

• They are made up of chains of carbon atoms surrounded by hydrogen atoms - they are a family of hydrocarbons
• They only contain single covalent bonds
• Alkane family contains molecules that look similar but they have different chain lengths due to the carbon atoms
• All have the same formula:
  • CnH2n+2
• First four are methane, ethane, propane and butane

• Alkanes burn to give carbon dioxide and water
  • alkane + oxygen ---> carbon dioxide + water
• You must give a balanced symbol equation for the burning of an alkane
• e.g. CH4 + 2O2 ---> 2H2O + CO2

• Alkanes don't react with most chemicals
• They don't react with aqueous reagents
• The C-C and C-H bonds are non-reactive

• -OH functional group
• General formula: CnH2n+1OH
• First two are methanol CH3OH and ethanol C2H5OH
• They have similar properties because of the -OH functional group

Alcohols, Alkanes and Water

• Ethanol is soluble in water, alkanes are insoluble in water
• Ethanol and water are both good solvents (lots of things dissolve in them)
• Boiling point of ethanol is 78 C, water is 100 C, ethane -103 C
• Ethanol is liquid at room temperature
  • Evaporates easily and gives out fumes (volatile)
• Methane and ethane are also volatile, but are gases at room temperature
• Water is liquid at room temperature but not volatile

• Alcohols are used as solvents and fuels and in manufacturing
• They can dissolve lots of compounds that water can't e.g. hydrocarbons and oils
• Makes ethanol and ethanol very useful solvents in industry
• Methanol is used in industries as a starting point for manufacturing other organic chemicals
• Ethanol used in perfumes and aftershave lotions
  • Can mix with both oils and water
• Methylated spirit (meths) is ethanol with chemicals added to it
  • Used to clean paint brushes and as a fuel
• Alcohols burn in air because they contain hydrocarbon chains
• Pure ethanol is clean burning so it is sometimes mixed with petrol and used as fuel for cars to conserve crude oil

• Alcohols react with sodium
• sodium + ethanol ---> sodium ethoxide + hydrogen
• Sodium metal reacts more vigorously with water - sometimes melting from heat
• sodium + water ---> sodium hydroxide + hydrogen
• Alkanes don't react with sodium at all

• Functional group -COOH
• Functional group gives them similar properties
• Their names end in '-anoic acid'

• e.g. methanoic acid

• They react with alkalis, carbonates, and reactive metals (just like other acids)
• Salts formed end in '-anoate' e.g. methanoic turns to methanoate
• React with metals to give a salt and hydrogen
• React with alkalis to give a salt and water
• React with carbonates to give a salt, water and carbon dioxide
• They are weak acids, so they don't react as fast as strong acids

• They have strong smells and tastes e.g. sweaty socks and rancid butter
• If wine or beer is left open, the ethanol is oxidised to ethanoic acid
• Vinegar is dilute concentration of ethanoic acid

ethanol + oxygen ---> ethanoic acid + water

• The strong smell and taste can sometimes be useful, like vinegar on chips