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^-1. A) 7.79 mol L^-1 B) 10.7 mol L^-1 C) 12.8 mol L^-1 D) 9.35 mol L^-1 E) 13.9 mol L^-1

Question

Quizplus · Accepted Answer

To find the molarity, first calculate the mass of HCl in 1 L of solution: 1.20 g/mL * 1000 mL = 1200 g solution. 39% of this is HCl, so 0.39 * 1200 g = 468 g HCl. The molar mass of HCl is approximately 36.46 g/mol, so the number of moles of HCl is 468 g / 36.46 g/mol = 12.8 mol. Therefore, the molarity is 12.8 mol/L.

Commercial Grade HCl Solutions Are Typically 39