Question

A 43.63 gram sample of a hydrate of caseo4 was heated thoroughly in a porcelain crucible, until its weight remained constant. after heating, 36.45 grams of the anhydrous compound remained. what is the formula of the hydrate?

Answer 1

let the hydrated compound be CaSO4.xH2O
mass of the caso4= 43.63g /(40+32+64+18x)* (40+32+64)= 36.45g
136+18x=( 43.63*136) / 36.45= 162.78
18x = 162.78- 136= 26.8
x = 1.48 = 1.5
Formula of hydrate = CaSO4.1.5H2O = 2CaSo4. 3H2O