General chemistry

Question

Commercial grade HCl solutions are typically 39.0% (by mass) HCl in water. Determine the molarity of the HCl, if the solution has a density of 1.20 g/mL.

Answer 1

Take 1000 mls of the solution as an example. In this case you have 1000 ml x 1.20 g/ml = 1200 g of solution.

1200 g x 0.39 HCl = 468 g HCl in that 1000 mls (1 L) of solution.

Molarity = moles HCl/liter of solution

moles HCl = 468 g HCl x 1 mol/36.5 g = 12.8 moles

Molarity = 12.8 moles/1 L = 12.8 M