C7: Alkanes and Alcohol

The Alkanes

• Molecules in the alkane family are hydrocarbons.
• Consisting only of hydrogen and carbon.
• Atoms with alkane molecules are joined together with single bonds.
• This means the molecules are saturated.
• Methane- simplest hydrocarbon molecule and the smallest of the alkane family: 1 carbon atom, 4 hydrogen atoms

Methane molecule

• Imagine the alkane molecules as being part of a family- next molecule in the series has a longer chain.
• Each time one more carbon atom is added and two more hydrogen.
• After methane comes ethane: C2H6.
• Methane, ethane, propane, butane, pentane, hexane, heptane,octane, nonane, decane...

Ethane Molecule

• Alkanes are used as fuels: they burn in air & release C02 and H2O.
• As chain length increases so does the boiling point.
• Alkanes do not react with aqueous substances: C-C & C-H bonds are unreactive.

Propane molecule

Alcohols

• Also organic molecules- but not hydrocarbons: oxygen is present.
• The hydroxy group gives alcohols its' characteristics: -OH.
• This is the functional group in an organic molecule.
• Methanol is the simplest alcohol

Methanol structure

• After methanol comes ethanol: C2H5OH.
• Alcohols burn in air = CO2 and H2O
• They are combustible because of the hydrocarbon in the chain.
• Alochol reacts with sodium less vigorously than sodium with water.
• Sodium replaces the hydrogen in the hydroxy group of the molecule.
• The products of the reaction are sodium ethoxide and hydrogen gas. 
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