Question

Find the mass percentage of MgCl2(aq) in a 1.58 L water solution containing 1.14 mol of MgCl2(aq). The density of the solution is 1.19 kg/L.

Answer 1

molar mass MgCl2 = 95.3 but you should confirm that.

g MgCl2 = 1.14 mols x 95.3 g/mol = 108.6 g in 1.58 L
mass 1.58 L = volume x density = 1.58 L x 1.19 kg/L = 1.88 kg.
% by mass = mass MgCl2/100 g solution. You have 108.6 g in 1.88 kg of solution or 108.6 g MgCl2 in 1880 g of solution. Convert to g MgCl2/100 g this way.
108.6 g MgCl2 x (100 g solution/1880 g solution) = ? about 6%