Question

Ten gram of hydrated calcium tetra oxo sulphate(vi) ( caso4 × H20 weighs 7.90g after heating and cooling. Calculate the empirical formula of the compound

Answer 1

CaSO4. 2H2O

Step-by-step explanation:

mass of hydrated salt = 10 g

mass of anhydrous salt = 7.90 g

molar mass of hydrated salt = 136 + 18x g/mol

molar mass of anhydrous salt = 136 g/mol

mass of hydrated salt/molar mass of hydrated salt = mass of anhydrous salt/molar mass of anhydrous salt

10.0/136 + 18x = 7.90/136

136 * 10 = 7.90 (136 + 18x)

1360 = 1074.4 + 142.2x

1360 - 1074.4 = 142.2x

285.6 = 142.2x

x = 285.6 / 142.2

x = 2

Hence the empirical formula of the compound is CaSO4. 2H2O