How would I find the percent of water lost in alum after it has dried for a week?

Question

Wet Alum = 13.44g
Dry Alum = 11.28g

Answer 1

I believe you would subtract the dry weight of the alum from the wet alum weight, then divide that answer by the original weight of wet alum:

13.44g(wet) - 11.28g (dry) = 2.16g of water that was lost.

2.16g H20/ 13.44g wet alum =0.1607 X 100 = 16.07% H20 lost

Hope this helps :)