Topic 1 - Organic Chemistry
The next few cards will include information on the following:
- Carboxylic acids
- Making Esters in detail
General facts about Alkanes
- Alkanes are a family of hydrocarbons
- The alkane formula is: CnH2n+2
Properties of Alkanes
- bigger alkane molecule --> stronger forces between molecules --> higher boiling point.
- insoluble as they are non-polar molecules (means that they do not have positive or negative ends like water molecules do).
- have strong C-C and C-H bonds meaning that they are very unreactive (except with oxygen). This is because a lot of energy is needed to break the bonds and also they are non-polar.
- alkanes are saturated molecules because they have single bonds. Alkenes are unsaturated because they have double bonds and this also means that they are more reactive.
- react with oxygen (combustion reaction) to make carbon dioxide and water.
General facts about Alcohols
- have an -OH functional group and their names end in '-ol'.
- the alcohol formula is: CnH2n+1OH
Properties of Alcohols
- weak acid as it does not fully dissociate. Reacts with metals and metal oxides/hydroxides just like HCl or any other strong acid would. Does not react with metal carbonates. Reacts with sodium to make salt and hydrogen gas.
- very flammable.
- soluble in water as they are polar molecules (have positive and negative ends like water molecules).
- strong inter-molecular bonds --> higher melting and boiling points.
They can be used as solvents, fuels and even as a starting point for the manufacturing of other organic chemicals.
General facts about Carboxylic acids
- have a -COOH functional group and their names end in '-anoic acid'.
Properties of Carboxylic acids
- oraganic weak acids as they do not fully dissociate. They react like any other acids would making the same sort of products.
- they are stronger than alcohols. They can react will metals (products = salt + hydrogen), metal oxides/hydroxides (products = salt + water) and metal carbonates (products = salt + carbon dioxide + water).
- insoluble in water as they are not defined polaric molecules.
They have strong smells and tastes. e.g. sweaty socks stick because of carboxylic acids; rancid butter tastes disgusting because of carboxylic acids; and vinegar!
Wine and beer tastes like vinegar (dilute ethanoic acid) after it is left open in air because the ethanol in wine and beer oxidises to make ethanoic acid.
General facts about Esters
- have a -COO- functional group.
- word equation for esterification reaction:
alcohol + carboxylic acid --> ester + water
Properties of Esters
- they are slightly polar however insoluble in water.
- they have a volatile property. Volatile means it evaporates easily.
Method of making Esters (explained in detail in the next card)
Refluxing --> Distillation --> Purification --> Drying
Fats and oils are esters made of glycerol and fatty acids. These can be saturated or unsaturated.
* arrow for this reaction should be the arrow going both ways indicating that the reaction is reversible + the reaction needs a catalyst (usually concentrated H2SO4.
Making Esters in detail
Making and Ester
1. Refluxing: the alcohol and ester are heated with a little concentrated H2SO4 in a flask with a condenser attached. The condenser prevents evaporation of the mixture.
2. Distillation: here the mixture is heated and the product collected at its boiling point. This separates the product from most of the impurities.
3. Purification: product is shaken with reagent in a separating funnel. Impurities dissolve in reagent (which can then be run off).
4. Drying: solid drying agent is added to product. The drying agent absorbs the water from the product. Filter the product to remove the solid drying agent from the product.