Determine the mass of BaF2

Question

A chemist wishes to prepare 200mL of a saturated solution of BaF2, the concentration of which is 6.3 x 10 to the -3 mol/L. Determine the mass of BaF2 that will be needed to make up the 200mL of the solution.

Answer 1

*atomic weight of Ba=137.327

atomic weight of F= 18.998

*molecular weight of BaF2 =137.327+( 2X 18.998) = 175.323

*200mL = 0.2 L

*6.3 X 10 to the -3 = 0.0063

Molarity = moles/liter

moles = weight/ molecular weight

>>>>Molarity= weight/ molecular weight /liter

Molarity= weight /molecular weight X liter

weight = Molarity X molecular weight X liter

=0.0063  X 175.323 X0.2

= 0.221 gm