[JazzyP]

Background: I recently did a chemistry experiment at school involving 2 unknown solutions that we had to identify by doing various tests.  The topics we had been studying in school involved group 2 metals and the halogens so we had a rough idea of what the solutions could be.  The two unknown solutions were labeled Y and Z, and from the results of the tests, I am fairly confident that Y is either calcium sulphate or magnesium sulphate and Z is either calcium chloride or magnesium chloride.  Solution Z was given to us preprepared but solution Y (assumed to be either magnesium or calcium sulphate), we had to prepare ourselves from two unknown reactants.  One reactant was a white solid made up of tiny crystals- it was similar to table salt in texture and appearance.  The other reactant was an unknown solution.  To make solution Y we reacted these two reactants together and heated them over a bunsen burner while stirring them until the solution boiled.  Then we took it off the heat and filtered it into a boiling tube as there was white solid that hadn't dissolved (which I assume is undissolved calcium or magnesium sulphate). 
Question:  I am unsure of what the unknown reactants could be and was hoping anyone could help.  I am thinking that the white solid could be magnesium/calcium oxide or magnesium/calcium hydroxide and the unknown solution could be sulphuric acid?  But I really don't understand why we heated the solution.  My current thoughts are to allow as much solute to dissolve as possible or to speed up the reaction.  Any suggestions as to what the reactants could be and why we heated them would be much appreciated.  Or if any of my suggestions might be right please could anyone just confirm them!  (just assume that solution Y is calcium or magnesium sulphate).

[Arkcon]

JazzyP:, a breathless block of text like that is hard for people to read, even for yourself -- did you notice you said the same thing twice?  So you can help youself understand what's happening, try to break you posting up into:

What you may have

What you did

What you observed

and What chemical concepts you've used in your conclusions.  You've mentioned twice what the salts were.  You don't tell us how you know that.  If you're wrong, this will be a very long thread, full of effort by us, that gives you incorrect help.