Concentrated nitric acid is 15.6M and has a density of 1.41g/mL. What is the weight percent of concentrated HNO3?

Molarity = mol / liters

since the molarity is given, we can assume that we have 1.0 Liters of solution

15.6 M = mol / 1 liters---> this means that we have 15.6 moles of HNO3

we need to convert these moles to grams using the molar mass of HNO3

molar mass HNO3 = 1.01 + 14.0 + (3 X 16.0) = 63.01 g/mol

15.6 mol HNO3 (63.01 g / mol) = 983 grams HNO3

now we have to determine the grams of solution using the assumption of 1 liters of solution and the density

1 liters = 1000 mL

1000 mL (1.41 g / ml) = 1410 grams solution

mass percent = mass of solute / mass of solution x 100

mass percent = 63.01 / 1410 x 100 = 4.47 %