What is the residue after filtering in step 2 and saturated solution in step 3 when preparing magnesium sulfate. Also, explain why magnesium sulfate crystals form during step 4. steps for preparing magnesium sulfate:
step 1: add excess magnesium carbonate to a small volume of dilute sulfuric acid until no more magnesium carbonate would react.
step 2: filter the mixture
step 3: heat the filtrate obtained from step 2 until it was saturated.
step4: allow the hot filtrate to cool to room temperature and then remove crystals which formed.