Discuss three unavoidable sources of error in Part 1

Question

(the synthesis of the crystals)
of this experiment
and identify the major factors
that would explain a less-
than-100% yield. Note: human error is not an acceptable answer.

Was the alum not dry enough for impurities to give a rise?

Answer 1

Isn't there still dissolved alum in the water? It should be saturated with alum.