Gypsum, CaSO_{4 *} 2 H₂O is used to manufacture cement. What is the mass percent of water in this compound?

 

mass percent of water is 20.91%

Step-by-step explanation

mass percent for water in gypsum calculated by the formula

mass percent of water =(mass of water /total mass of CaSO4.2H2O) x 100

total mass of gypsum is

molar mass of Ca=40.078gmol^-1

molar mass of H=1gmol^-1

molar mass of S=32.06gmol^-1

molar mass of oxygen =15.999gmol^-1

so total mass of the gypsum is =40.078+32.06+(4x1)+(6x15.999)

total mass of gypsum =172.132gmol^-1

total mass of 2 molecule of water =35.998gmol^-1

put these values in the formula given above

mass percent of water =(35.998gmol^-1/172.132gmol^-1) x100

mass percent of water =20.91%