How to write an answer for AS 2.1

*Important You must write down all Observations You must back these observations up with all ionic equations

*Important Identifying Aluminium ion Observations When NaOH is added to the unknown a white precipitate of aluminium hydroxide is formed The reaction is: Al OH - Al(OH) 3

*Important for the complex forming test The reaction is: Al OH - Al(OH) 3 Observations When further NaOH solution is added the Al(OH) 3 precipitate dissolves to form a colourless solution indicating the formation of a complex Observations When NaOH is added to the unknown a white precipitate of Al(OH) 3 forms. Al 3+ + OH - [Al(OH) 4 ] - The reaction is: Yes you must repeat yourself !

How it all looks Description of test(s) carried out and observations Test for cation  addition of 2 drops of NaOH produces a white precipitate of Aluminium Hydroxide  excess NaOH added the precipitate dissolves  New sample with 2 drops of NH 3 gives white ppt of Aluminium Hydroxide  Then excess NH3 added the ppt remains  To a new sample addition of H 2 SO 4 results in colourless solution (showing ion is Al 3+ rather than Pb 2+ ) Formula or name of each precipitate formed Balanced equations for the formation of any precipitates Balanced equations for the formation of any complex ions  Al(OH) 3 (s)  Al(OH) 3 (s)  Al 3+ (aq) + 3 OH  (aq)  Al(OH) 3 (s)  Al 3+ (aq) + 3 OH  (aq)  Al(OH) 3 (s)  Al 3+ (aq) + 4OH  (aq)  [Al(OH) 4 ]  (aq)