Question

A chemist needs to make up a solution containing 300 mg/L of magnesium (as Mg2+). The magnesium salt available in the lab is magnesium chloride hexahydrate and the product contains 1% impurities. The salt’s contribution to the total solution volume is considered to be negligible.

Calculate the required quantity of magnesium chloride hexahydrate in order to make up the required solution.

MW Mg= 24.31

MW Cl= 35.45

MW O = 16.00

MW H = 1.01

Answer 1

MW Mg= 24.31

MW Cl= 35.45

MW O = 16.00

MW H = 1.01

Now, Mw of MgCl₂(H₂O)₆=203.4

Now, solution required to be is (300/100)/mol

=0.3g/mol.

Now the required amount of the salt is given by, 203.4/.3=678g.