A concentrated hydrochloric acid solution has a density of 1.19 g/mL at 25°C and is 12.1 M.What is the percent by mass of HCl in the solution?
A) 37.1% HCl by mass
B) 1.02% HCl by mass
C) 0.980% HCl by mass
D) 2.80% HCl by mass
E) 30.6% HCl by mass

Question

Quizplus · Accepted Answer

First, we need to use the density and molarity of the solution to calculate the mass percent of the HCl. To do this, we need to know the molecular weight of HCl, which is 36.46 g/mol.

At 25°C, the density of the solution is 1.19 g/mL, which means that 1 L of the solution would weigh 1190 g (1.19 g/mL x 1000 mL/L).

To calculate the mass of HCl in 1 L of the solution, we can use the molarity:

12.1 mol HCl/L x 36.46 g/mol HCl = 441.67 g HCl/L

To convert this to a mass percent, we divide the mass of HCl by the total mass of the solution and multiply by 100%:

441.67 g HCl/L / 1190 g/L x 100% = 37.1% by mass

Therefore, the correct answer is (A) 37.1% HCl by mass.

A Concentrated Hydrochloric Acid Solution Has a Density of 1