C7 - Alkanes, Alcohols, Carboxylic Acids, Esters.

C7 revision.

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Alkanes

Alkanes are a family of hydrocarbons
Made up of chains of carbon atoms surrounded by hydrogen atoms
Contain single covalent bonds
Different length carbon atom chains
The formula - CnH2n+2

Methane, Ethane, Propane, Butane.
CH4            C2H6     C3H8        C4H10

They burn to give Carbon Dioxide AND Water
alkane+oxygen = carbon dioxide + water

They don't react with most chemicals
Don't react with aqueous reagents (substances dissolved in water)
Unreactive as the C-C bonds and C-H bonds are unreactive.

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Alcohols

Alcohols have an '-OH' functional group and end in '-ol'
Formula = CnH2n+1OH
Methanol - CH3OH and Ethanol - C2H5OH
All have similar properties

Ethanol is soluable in water, alkanes are insoluable.
Ethanol and water are good solvents
Ethanol boiling point - 78degreesC, higher than the boiling point of an alkane - (-103degreesC for ethane)
Ethanol is liquid at room temperature, evaporates easily and gives off fumes (volatile) Methane and Ethane are volatile but gases at room temp

Alcohols are used as solvents and fuels in manufacturing
Can dissolve eg. hydrocarbons and oil
Ethanol - perfume and aftershave and mix with oil and water

Reacts with sodium
Sodium +ethanol = sodium ethoxide +hydrogen
Sodium + water = sodium hydroxide + hydrogen

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Carboxylic Acids

Functional Group - '-COOH'
Similar properties
End in 'anoic acid' and start with 'meth/eth..'

They are reactive - with alkalis, carbonates and reactive metals
The salts formed end in '-anoate' eg, methanoate acid

Carboxylic acid + magnesium = magnesium ethanoate + hydrogen
(acid + metal = salt + hydrogen)
Ethanoic acid + magnesium hydroxide = magnesium ethanoate + water
(acid + alkali = salt + water)
Ethanoic acid + magnesium carbonate = magnesium ethanoate + water + C02
(acid + carbonate = salt + water + carbon dioxide)

Weak acids, as they don't react as fast as strong acid like hydrochloric

Strong smelling
If wine or beer is left open the ethanol is oxidised into ethanoic acid - vinegar.

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Esters

Functional group - '-COO-'
Family of organic chemicals
Alcohol and carboxylic acid - esterfication
Alcohol + carboxylic acid --- ester + water

Used in flavourings and perfumes
Ointments (deep heat)
Solvents (paint, ink, glue)
Platicisers (more flexible)

Fats and oils are esters of glycerol and fatty acids
Fatty acids are caboxylic acids - 16-20 carbon atoms
Glycerol is an alcohol (-OL)
FA can be saturated (C-C) single bonds. Or unsaturated (C=C) double bonds

Plants and animals make oils and fats to store energy
Animal fats are usually saturated hydrocarbon atoms, few C=C bonds, normally solid at room temp. Vegetable oil have mainly unsaturated hydrocarbon chains, lot's of C=C bonds, normally liquid at room temp.

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Comments

Hanh

Thanks!! :)

Beth Vickers

Thankyou :)

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