How accurate is an experimental formula - what can be made?
some assumptions and real experiments may not always work out as well
Assumption 1 - If the hydrated and unhydrous forms have different colours, what can you then be sure?
that all water has been removed
Assumption 1 - What can you only see?
the surface of the crystals and some water could be left inside
Assumption 1 - If the hydrated and anhydrous forms are similar colours, what does this suggest?
that it is not as easy to determine if all the water has been lost
Assumption 1 - What could be a good solution?
to heat to constant mass - the crystals are reheated repeatedly until the mass of the residue no longer changes - this shows that all water has been removed
Assumption - What decomposes further when heated?
Assumption 2 - For example, if heated strongly, what happens to copper (II) sulfate?
it decomposes to form black copper (II) oxide
Assumption 2 - What is difficult to judge if there is further or no further decomposition?
if there is no colour change