Question

A concentrated HCl solution is described in the bottle as containing 36%(mass by volume) of HCl.what is the molar concentration of this volume?

Answer 1

You need the density of the solution. If the density is `1.18` `g"/"cm^3`, the molarity is about `12` `mol"/"L`.

Explanation:

Suppose the density of the concentrated `HCl` solution is `1.18` `g"/"cm^3`.
https://wissen.science-and-fun.de/chemistry/chemistry/density-tables/density-of-hydrochloric-acid/

Then, take `1` L of the solution.
Its mass is `1000(cm^3) * 1.18 (g"/"cm^3)=1180` g, and it contains `1180 (g) * 36/100 = 425 (g)` of hydrochloric acid.

The molar mass of `HCl` is `36.5 (g"/"mol)`. `1` L of the concentrated solution contains `(425(g)) /(36.5 (g"/"mol))=11.64…~=12` moles of `HCl`.