the_pope - 28-1-2015 at 15:50
Sulfuric acid added to magnesium chloride produces MgSO4 and HCl fumes. What if MgCl2 would be dissolved in water and immediately after adding H2SO4,
the flask holding the mixture would be stoppered, forcing the fumes into the water?
Would the HCl react with magnesium sulfate? Would one eventually end up with a mixture of MgCl2, MgSO4, H2SO4 and HCl?
subsecret - 28-1-2015 at 16:41
All the ions will be dissolved, so it's not really a question of whether the compounds would be present. Combine Mg++, H+, Cl-, and SO4-- how you
will, and that's what'll be in your solution. If you want the reaction to be reversed completely, you'll have to find a way to remove products.
Oscilllator - 29-1-2015 at 16:33
the_pope your question reveals a very common misconception many people have about ionic compounds.
When they are in solution, many people seem to think that they are still present as the original molecule, i.e. MgSO4 dissolved in water is still
MgSO4. It is not, the Mg2+ ions and SO42- ions are separated, and move about in the liquid on their own.
This means that if you dissove MgCl2 and H2SO4 in water, you will get the ions Mg2+, H+, Cl- and SO42- just as Awesomeness has said. However if you
were to dissolve MgSO4 and HCl into water, you would get exactly the same thing.
If you had used CaCl2 instead of MgCl2, you would have got a precipitate of CaSO4 because that is insoluble in water. In this case we could say that
you had a solution of HCl in water, even though in reality what we mean is a solution of H+ ions and Cl- ions in water.*
There are of course cases where you can mix two ionic substances and they do chemically react, such as an acid with sodium thiosulphate, however I'll
leave that explanation for another day.
*I'm leaving out the whole H3O+ stuff here for clarity