A volume of 150mL of 0.35M HCl is to be prepared from 80% HCl stock solution. (Density of HCl = 1.191g/mL). Calculate the molarity of 80% HCl stock solution.

Answer 1

density 1.191 g/mL.
mass 1000 mL = 1.191 g/mL x 1000 mL = 1191 g.

mass HCl in that 1L = 1191 x 0.80 = 952.8 g HCl.

mols HCl = grams/molar mass = 952.8/36.46 = 26.13 mols HCl.
M = mols/L = 26.13/L = 26.13M BUT let me point out that this can't be so. The calculations are right so this will show you the procedure by which it's done; however, the most concd you can get HCl is about 38% HCl. There is no such animal as 80% HCl. Concentrated HCl solutions available commercially, containing 36-38% HCl are about 12 M.