Las disoluciones comerciales de HCl (PF = 36.5 g/mol) típicamente son 39.0% P/P de este ácido en agua. Determine la molalidad de la disolución del HCl si la densidad de la misma es igual a 1.20 g/ml.

The translation of the question is

Commercial solutions of HCl (MP = 36.5 g / mol) are typically 39.0% W / W of this acid in water. Determine the molality of the HCl solution if its density is equal to 1.20 g / ml.

Molality is 17.51 molal

Explanation:

We are given 39% w/w of HCl, this means for every 100g of this solution we have 39g of HCl in it.

to ease the calculation we assume we have 1L(1000ml) of this solution is present.

Density = mass /volume

1.20 = mass/1000

mass = 1200 g of solution

and we are given that 39% of this solution is will contain HCl

so

1200 * 39/100 = 468g of HCl present

no of moles of HCl = 468/36.5 = 12.82moles

mass of solution = mass of water + mass of acid

mass of water = mass of solution - mass of acid

Mass of water = 1200 - 468 = 732g of water

Molality = moles /masss of water in kg

             = 12.82 *1000/732  =17.51molal

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