3.4 Recall the products of the complete and incomplete combustion of alkanes

Complete combustion of alkanes will give you carbon dioxide and water

Incomplete combustion will give you carbon monoxide and water

3.3 Draw displayed formulae for alkanes with up to five carbon atoms in a molecule, and name the straight-chain isomers

All you need to remember when drawing displayed formulas for alkanes is that every carbon is bonded to two hydrogens (usually draw them one on top and one below) and there are two hydrogens on the end of the whole thing.

Below is the displayed formula for
1. Methane


2. Ethane
 

3. Propane


4. Butane


5. Pentane

1.23 Understand how the formulae of simple compounds can be obtained experimentally, including metal oxides, water and salts containing water of crystallisation

• Weigh the compound
• Remove one element of it through a reaction
• Weigh again
• If the first weight [mass] of the compound is AB and the second weight [mass] is A, you can work out B by: AB-A=B
• Work it out by dividing the weight by the relative atomic mass

3.2 Recall that alkanes have the general formula CnH2n+2

If you see the post tagged 3.1, a general formula is a formula that all members of a homologous series (in this case, the alkanes) will fit.

Basically (in every single alkane) for every carbon atom there will be twice the amount of hydrogen plus two.
- E.g.: 2 carbons
-         2(2) + 2 hydrogens = 6 hydrogens

3.1 Explain the terms homologous series, hydrocarbon, saturated, unsaturated, general formula and isomerism.

HOMOLOGOUS SERIES: 
"A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula" (BBC Bitesize). Basically, compounds (in this case hydrocarbons) in the same homologous series have the SAME general formula and SIMILAR chemical properties

HYDROCARBON
A compounds made up of ONLY hydrogen and carbon atoms

SATURATED 
A compound is described as 'saturated' if it ONLY has single bonds present. This means that the compounds has "bonded as many times as possible" (Hannah Help). 

UNSATURATED
A hydrocarbon with a double carbon carbon bond is described as unsaturated, because more bonds can be made (as can be seen later in polymerisation)

GENERAL FORMULA
A formula that all members of the same homologous series will fit.

ISOMERISM
Compounds with the same chemical formulas, but different structural formulas

2.38 Describe tests for anions

i) USING DILUTE NITRIC ACID & SILVER NITRATE SOLUTION (depending on the precipitate)

• Chloride ions (Cl-) + nitric acid + silver nitrate > white precipitate 
• Precipitate = silver chloride
• Bromide ions + nitric acid + silver nitrate > cream precipitate 
• Precipitate = silver bromide
• Iodide ions + nitric acid + silver nitrate > yellow precipitate 
• Precipitate = silver iodide

ii) USING DILUTE HYDROCHLORIC ACID & BARIUM CHLORIDE SOLUTION

• Sulphate ions + hydrochloric acid + barium chloride > white precipitate
• SO4(2-) + HCl + BaCl2 (2+) > BaSO4
• Precipitate = barium sulphate

iii) USING DILUTE HYDROCHLORIC ACID (& identifying if CO2 is produced)

• Carbonate + hydrochloric acid > salt + water + carbon dioxide
• Test for CO2:
• When bubbled through lime water, will turn it cloudy

2.37 Describe tests for the following cations:

i) FLAME TESTS

• Li+ (Lithium) burns with a red flame
• Na+ (Sodium) burns with a strong orange flame (sometimes it is so strong it can mask other colours)
• K+ (Potassium) lilac flame
• Ca2+ (Calcium) burns with a brick red flame

ii) NH4+ USING SODIUM HYDROXIDE SOLUTION (& identifying the ammonia produced)

• ammonium ions + hydroxide ions > ammonia + water
• (NH4 + OH > NH3 + H2O)
• How to test for ammonia: 
• ammonia will turn red litmus paper blue
• it also has a 'pungent' smell

iii) USING SODIUM HYDROXIDE SOLUTION (CU2+, FE2+, FE3+)

• Copper (ii) sulphate + sodium hydroxide > blue precipitate
• CuSO4 + NaOH
• Iron (ii) sulphate + sodium hydroxide > green precipitate
• FeSO4 + NaOH
• Iron (iii) sulphate + sodium hydroxide > brown precipitate
• Fe2(SO4)3 + NaOH