What mass of iron(III) chloride contains 4.13 1023 chloride ions?

37.3g

Explanation:

Formula of the compound:

          FeCl₃

Number of chloride ions  =  4.13 x 10²³ ions

First find the number of moles in this ions;

         6.02 x 10²³ ions are contained in 1 mole of a substance

         4.13 x 10²³ ions contains  = 0.69mole chloride ions

Now;

        3 mole of chloride ions are contained in 1 mole of FeCl₃

       0.69 mole of chloride ions will contain = 0.23mole of FeCl₃

To find the mass;

         Mass of FeCl₃ = number of moles x molar mass

 molar mass of FeCl₃ = 55.8 + 3(35.5)  = 162.3g/mol

        Mass of FeCl₃ = 0.23  x  162.3  = 37.3g

it means there are 3 atoms of oxygen