Question

Suppose we have a compound that is 4.330 % Li, 22.10 % Cl, 39.89 % O, and 33.69 % H2O. What is the compounds formula?

Answer 1

The  formula   of compound is   LiClO4.3H2O

      calculation

•  find the mole  of  each element

        that is  moles for Li,Cl,O and that of H2O

• moles = % composition/ molar mass

       For Li = 4.330/ 6.94 g/mol=  0.624 moles

             Cl=22.10/35.5=0.623  moles

           39.89/16 g/mol =2.493  moles

           H20=  33.69/18 g/mol=  1.872  moles

• find  the mole ratio  by  dividing each moles by smallest number of mole ( 0.624 moles)

        that  is  for  Li= 0.624/0.623=  1

                             Cl= 0.623/0.623=1

                             O = 2.493/0.623 =4

                          H2O= 1.872/0.623=3

Therefore the formula=LiClO4.3H2O