# Question #a6c51

Mar 26, 2017

The molarity is 12 mol/L.

#### Explanation:

The density of concentrated $\text{HCl}$ is ${\text{1.18 g/cm}}^{3}$.

Assume that you have ${\text{1 dm}}^{3}$ of conc. $\text{HCl}$.

Then

$\text{Mass of HCl solution" = 1000 color(red)(cancel(color(black)("cm"^3 "HCl solution")))× "1.18 g HCl solution"/(1 color(red)(cancel(color(black)("cm"^3 "HCl solution")))) = "1180 g HCl solution}$

$\text{Mass of HCl" = 1180 color(red)(cancel(color(black)("g HCl solution"))) × "36 g HCl"/(100 color(red)(cancel(color(black)("g HCl solution")))) = "425 g HCl}$

$\text{Moles of HCl" = 425 color(red)(cancel(color(black)("g HCl"))) × "1 mol HCl"/(36.46 color(red)(cancel(color(black)("g HCl")))) = "12 mol HCl}$

∴ The molarity of the solution is 12 mol/L.

Note: The answer can have only 2 significant figures, because that is all you gave for the concentration of the acid.