Homologous series

Hydrocarbon Definitions:  

Empirical Formula: Smallest whole number ratio of a compound.  

Molecular Formula: The actual number of atoms of each element in a compound 

General Formula: Alkanes = CnH2n+2, Alkenes = CnH2n , Alcohols = CnH2n+1OH 

Structural Formula: Shows all the carbon bonds in a compound but nothing else.  

Displayed Formula: Shows all atoms and all bonds in a compound 

Homologous Series, Functional Group & Isomerism 

-HS= a family of hydrocarbons that have the same general formula but different chemical properties.  

-FG = the substituent molecule like -OH or -COOH that causes a compounds unique characteristics.  

-I = molecules with the same molecular formula and a different arrangement of atoms.  

Alkanes: 

-They are their own homologous series. They have the suffix -ane.  

-Saturated hydrocarbon meaning that all carbon atoms have 4 bonds and it contains hydrogen and carbon only.  

Alkenes:  

-There are carbon atoms which again have 4 bonds but there is a C=C.  

-Test for an alkene it will turn Bromine water colourless from orange.  -Addition reaction that can take place in a test tube but also in steam addition reaction.  

Alcohols 

-They have the suffix -OL i.e. Butanol, Propanol.  

-Don't put C2H6O put C2H6OH. 

-You can make Alkenes and water from an alcohol by dehydration.  

-For dehydration to work you need Heat + acid catalyst (Phosphoric acid) 

-Can also be made by fermentation.  

-This process requires yeast. The starting reactant is Glucose C6H12O6 

-Conditions will need to be about 30 degrees celcius.  

-The boiling point of alcohol is much lower than water. 78 degrees for ethanol. 

 Addition Polymerisation:  

-A polymer is made from joining multiple monomers together forming polymer (long chains)  

-To name the polymer = poly(alkene), poly(ethene) or poly(propene). (C₂H₄)_n 

-A monomer makes up the addition polymers.  

-To carry out this reaction you need both a catalyst and pressure.  

Properties:  

Poly(ethene)  

-Flexible and cheap, also a good electrical insulator.  

-Carrier bags, plastic water bottles, wire insulation. 

 
Poly(propene)  

-Flexible, strong, tough and Mouldable  

-Ropes and plastic boxes 

Poly(chloroethene) PVC  

-Tough, cheap 

-Pipes, window frames 

Poly(tetrafluoroethene) PTFE 

-Tough and non-stick  

-Waterproof clothing and non stick pans.  

Carboxylic Acids:  
-Functional group is COOH  

-Methanoic Ethanonic, Propanoic, Butanoic etc.  

-To make carboxylic acids you take an alcohol and oxidse it with an oxidising agent.  

-Potassium Dichromate as the oxisiding agent.  

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-Carboxylic acids are weak acids though behave like acids i.e. form salt + water + CO2 when reacting with carbonates.  

Esters:  

-Made by esterification from and alcohol and carboxylic acid. 

-Used for perfumes and flavourings 

-The condition for esterification is an acid catalyst  

-To name you take the alcohol first then the carboxylic acid.  

-If you had propanol with methanoic acid = propyl methanoate