Calculate the molality of a 10.0% (by mass)aqueous solution of hydrochloric acid.
A)0.274 m
B)2.74 m
C)3.05 m
D)4.33 m
E)The density of the solution is needed to solve the problem.

Question

Quizplus · Accepted Answer

To calculate the molality of the solution, we need to know the moles of solute (HCl) and the mass of solvent (water).

Assuming that the density of the solution is 1.00 g/mL, we can convert the mass percentage of HCl to grams of solute:

10.0% by mass means 10.0 g of HCl per 100.0 g of solution
Thus, we have 10.0 g HCl / (36.5 g/mol) = 0.274 moles of HCl

To find the mass of solvent, we subtract the mass of solute from the total mass of the solution:

100.0 g solution - 10.0 g HCl = 90.0 g H2O

Now we can use these quantities to calculate the molality:

molality = moles of solute / mass of solvent (in kg)
molality = 0.274 mol / 0.090 kg = 3.05 m

Calculate the Molality of a 10