Question

Calculate the formula unit mass of $CaS{O}_{4.}2H_{2}O$.

Answer 1

Formula unit mass of $CaS{O}_4.2H_{2}O$

$=$ (Number Calcium atoms x atomic mass of Calcium) + (Number Sulphur atoms x atomic mass of sulphur) + (Number Oxygen atoms x atomic mass of Oxygen) + (Number Water molecules x Molecular mass of water molecule)

$=(1\times 40)+(1\times 32)+(4\times 16)+(2\times 18)$

$=40+32+64+36$

$=172$

Formula unit mass of gypsum = 172