- Created by: callum
- Created on: 21-05-11 17:09
Alkanes are a family of hydrocarbons. Hydrocarbons are made up of carbon and hydrogen only.
some examples of hydrocarbons are:
methane (ch4), ethane (c2h6), propane (c3h8) and butane (c4h10)
when alkanes burn in air their combustion products are, carbon dioxide and water.
Alkanes are good fuels. We burn methane to cook, heat and generate electricity.
Alkanes do not react with acids or alkalis because their c-c and c-h bonds are unreactive
Alcohol molecules contain an: -OH functional group.
Examples of Alcohols are Methanol (CH3OH) and Ethanol (C2H5OH)
Ethanol can be used:
- as a solvent - as a fuel - in drinks like beer
Methanol and Ethanol mix well because there -OH group is similar to waters.
long Hydrocarbon chains do not interact with water molecules.
Alcohols tend to have high boiling points because their -Oh groups tend to pull its molecules together.
Alcohols contain a hydrocarbon chains so they burn in air to make CO2 and H20
Water and Ethanol react similarly with Sodium because they both have and -OH group. Alkanes dont react with sodium as their c-c and c-h bonds are unreactive
Carboxylic acids contain a: -COOH Functional group
Examples of Carboxylic acids are Methanoic acid (HCOOH) and Ethanoic acid (CH3COOH).
Some Carboxylic acids smell and taste bad such as vinegar which is a dilute solution of Ethanoic acid.
When a Carboxylic acid disolves in water the hydrogen ions leave the functional group.
Carboxylic acids are weak acids because: only a few molecules are ionized at any one time.
Esters contain this functional group: -COO
Esters cause smells and flavours of fruits. some uses for Esters are:
- To flavour food - Sweet smelling perfumes - Solvents - Plastisizers
You can make an ester by warming a mixture of an Alcohol and carboxylic acid. A small amount of sulphuric acid is also needed as a catalyst.
Ethanoic acid + Methanol -----> Methyl ethanoate + water
( Carboxylic acid) (Alcohol) (Ester)
Fats and Oils
Plants and animals make Fats and Oils as energy stores.
Fats and oils are Esters of glycerol and fatty acids.
Animal fats like butter and lard are usually solid at room temperature. All carbon bonds are single ( C-C ). The molecules are saturated, meaning no mo hydrogen can be added to them.
Vegetable oils like sunflower oil are usually liquid at room temperature. Some of their carbon bonds have double bonds ( C=C ). The molecules are unsaturated meaning more hydrogen atoms can be added.