Molarity from density?

Question

A solution containing 296.6 g of Mg(NO3)2 per liter has a density of 1.114 g/mL. What is the molarity of the solution?

Answer 1

first calculate the molar mass of Mg(NO3)2 in g/mol (you should have tables in your textbook?). determine the number of moles by dividing the mass (296.6 g) by the molar mass. the molarity is equal to this number since the mass per liter is given. the density is not useful, since the solution is not a pure liquid.