Topic: Technique - synthesis
Purpose: to determine the percetage of aluminium in a sample X by means of the preparation of a complex compoun dof aluminium wiht 8-hydroxyquinoline.
Let's assume that the result of step (a) obtained as below:
mass of container + KA3/ g = x
mass of empty container/ g = y
mass of KA3/ g = x-y = z
Let's the result of step (b) as below:
mass of crucible + precipitate/ g = a
mass of empty crucible/g = b
mass of precipitate/g = a - b = c
(c) (i) to maximised the collision between particles and thus ensures a complete reation
(ii) to remove impurities and excess ions. Cold water ensures that no precipitate will dissolve and be washed away because water with low temperature will not dissove the precipitate.
(d) the complex precipitate obtained is dried and weight a few times in the oven until the weight of the complex precipitate obtained is constant.
(e) Mass of 1 mole of complex compound with formula Al(C9H6NO)3 = 459.0 g
(f) Percetage of aluminium in the complex compound = 27.0 / 459.o x 100% = 5.88%
(g) weight of aluminium produced = 5.88/100 x c = m1 g
therefore, the percetage of Al in sample X = m1/z x 100% = p %
All the best!