1. Identifying Compounds
Definitions
Ion: a charged atom
Anion: a negatively charged ion
Cation: a positively charged ion
Tests for Positive Ions
Element
Colour
Lithium
Sodium
Barium
Potassium
Calcium
Flame test colours
Li – bright red
Na – golden yellow
Ba – green
K – lilac
Ca – brick red
Tell the difference between Al, Ca and Mg
Keep adding H2SO4, if the precipitate dissolves, the compound contains Al ions
Ca and Mg can be distinguished by flame tests – Ca gives a brick red colour, Mg no colour at all
Reactions with Sodium Hydroxide
Add Sodium Hydroxide to the solution:
White precipitate = Al, Ca or Mg ions
If warmed and turns red litmus blue = ammonium ions (NH4+)
Coloured precipitate
Light blue = copper
Dirty green = iron (II)
Reddish brown = iron (III)

2. Tests for Negative Ions
Complete the diagram
Unknown solution: add sodium hydroxide solution
White
precipitate
Al3+
dissolves in excess sodium hydroxide
Insoluble in excess sodium hydroxide
Ca2+
Mg2+
Light blue precipitate
Dirty green precipitate
Reddish-brown precipitate
Warm through
Red litmus turns blue
Coloured precipitate
Tests for Negative Ions
Carbonates
You can add dilute _____________ _________ to a carbonate. If it fizzes and produces ______ _________ gas, the test is positive. You can check for the gas by using _________ __________ which will go _______.
Two carbonates have distinct colour changes when heated
Copper Carbonate  Copper Oxide + Carbon Dioxide
( ) ( )
Zinc Carbonate  Zinc Oxide + Carbon Dioxide
( ) ( )
Write balanced word equations for the reactions above:
Copper Carbonate:
Zinc Carbonate:

3. Ag+ (aq) + X (aq) AgX (s)
Halides
The Halides are any compound formed with a Halogen
e.g. Chlorine, Bromide and Iodide
We can add _______ __________ and dilute _______ _____ to a compound to see if it is a halide. The colour of the precipitate tells us which Halide is present:
Chlorine:
Bromine:
Iodine:
The general ionic equation for the formation of this precipitate is:
Ag+ (aq) + X (aq) AgX (s)
Sulfates
Sulfates are any compound with a sulfate group (SO4),
In solution, they produce a _________ precipitate when we add ___________ ______ followed by __________ _________ solution. The precipitate is the insoluble salt, Barium Sulfate.
The ionic equation for this is:
Ba2+ (aq) + SO42-  BaSO4 (s)

4. Nitrates Organic substances
Nitrates can be detected by use of the same test we use for ammonium ions: adding sodium hydroxide, __________ the solution through and testing with _______ _________. If no ammonia is given off, we can add a little aluminium powder. This reduces the nitrate ions to ammonium ions, and they can then react with the sodium hydroxide to form _________ gas, which will turn _____ litmus paper ______.
Organic substances
Organic substances are those which contain mainly _______ in combination with other substances.
Inorganic substances are those which consist mainly of other elements, which are not ________.
Write a short paragraph explaining how we can detect carbon-carbon (double, C=C) bonds using bromine water. Write a word equation showing the reaction for saturated and unsaturated compounds.