Question

Calculate the molarity of a solution made by adding 25.4 mL of concentrated hydrochloric acid (37.3 % by mass, density 1.19 g/mL) to some water in a volumetric flask, then adding water to the mark to make exactly 500 mL of solution. (It is important to add concentrated acid or base to water, rather than the other way, to minimize splashing and maximize safety.)

Answer 1

Solution :-

Lets first calculate the mass and moles of the HCl present in the original solution

Mass of solution = volume * density

                               = 25.4 ml *1.19 g per ml

                              = 30.226 g

Mass of HCl = 37.3 % * 30.226 g / 100 % = 11.27 g HCl

Now lets calculate the moles of HCl

Moles of HCl = 11.27 g / 36.5 g per mol

                        =0.3088 mol HCl

Now lets calculate the molarity of the diluted solution

Molarity = moles / volhume in liter

                 = 0.3088 mol HCl / 0.500 L

             = 0.6176 M

So the molarity of the diluted solution is 0.6176 M