Yesterday I had a practical examination, and one question involves the heating of FeSO4.xH20 to get rid of the water of crystallization to determine the value of x. A crucible was used to contain the crystals. Just a few grams. I had found the value of x to be 7. And now a part of the question says, a student did the same experiment and obtained a value of 9. What could be the reason for this? I wrote that because during heating some of the FeSO4 crystals "jump" out from the crucible, resulting in a larger mass loss and the mass lost is assume to be the mass of water of crystallization. Is that acceptable?