Question

Concentrated hydrochloric acid has a purity of 36.0% by mass. The density of the concentrated of the acid is 1.19 g/mL.Determine the molar concentration of this acid..please show me the solution...

Answer 1

M = mols/L so you want to know how many moles HCl there are in 1 L.
1000 mL weighs how much?
That's 1000 mL x 1.19 g/mL = 1190 g
How much of that is HCl? Only 36%; therefore, g HCl = 1190 x 0.36 = estimated 428g
How many mols is that? mol = g/molar mass
mols = 428/36.5 = estimated 12 mol.
So you have about 12 mol in 1L which makes it about 12M.
I like to do these in one step. You can identify each step from the above step by step.
1000mL x 1.19g/mL x 0.36 x (1 mol/36.5g) = ?M