Question

Calculate the Molarity of hypothetical 16.26% (by mass) aqueous HCl solution. The solution has a density that is higher than water due to the nature of the solute solvent interactions. Suppose the density of this particular solution is 1.076g/mL.

Answer 1

Solution:

Molarity (M) indicates the number of moles of solute per liter of solution (moles/Liter)

M = n (moles of solute) / V (liters of solution)

The common unit for molarity are mol/L or mol/m³.

Assume some fixed mass of the solution. For convenience, let's assume a mass of 100 grams.

16.26 g HCl + 83.74 g H₂O = 100 g solution

Mass % = $(mass solute)/(mass solution)×100$ %

Molar mass of HCl 36.45 gram/mol

1. Calculate a volume of solution

V =  $(100 g solution)/1×(1 ml)/(1.076 g)×1l/1000ml$ = 0.0929 L

2. Calculate molarity M

 $(16.26 g HCl)/1×(1mol HCl)/(36.45 g)×1/0.0929L$ = 4.80 mol/L

Answer: Molarity of HCl solution is 4.80 M.