J.R. S. answered 05/17/21
Ph.D. University Professor with 10+ years Tutoring Experience
molar mass Mg(NO3)2 = 148.3 g/mol
how many moles are in 88 g? 88 g x 1 mol / 148.3 g = 0.593 mols Mg(NO3)2
0.31 M = 0.31 mols Mg(NO3)2 / L
(x L) (0.31 mols / L) = 0.593 mols
x = 1.91 L contains 0.593 mols which is 88 g of Mg(NO3)2