Question

A 2.914 gram sample of gypsum, a hydrated salt of calcium sulfat, CaSO4, is heated at a temperature greater than 170 degrees Celcius in a crucible until a constant mass is reached. The mass of the anhydrous CaSO4 salt is 2.304 grams. Calculate the percent by mass of water in the hydrated calcium sulfate salt

Answer 1

2.914-2.304 = loss in mass = mass H2O lost.
%H2O = (mass H2O/mass sample)*100 = ?

Note: A more interesting problem is to calculate the formula of the hydrated CaSO4 from these data.

Answer 2

1.88