# What is the mass concentration of "0.05 N" "HCl"?

Aug 18, 2016

Normally (pun intended?), normality would tell you the equivalent concentration of protons for a given acid. So if you had $\text{1 M}$ ${\text{H"_2"SO}}_{4}$, it would actually be $\text{2 N}$ ${\text{H"_2"SO}}_{4}$, since there are two protons per molecule of ${\text{H"_2"SO}}_{4}$.

However, since $\text{HCl}$ is monoprotic, $\text{0.05 N HCl}$ $=$ $\text{0.05 M HCl}$.

Therefore, you should have $\text{0.05 mols HCl"/"L soln}$, or:

$\text{0.05" cancel"mols HCl" xx "36.4609 g HCl"/cancel"1 mol HCl}$

$= \textcolor{b l u e}{\text{1.82 g HCl"/"L soln}}$

Even though $0.05$ has only one sig fig, realistically you could easily measure at least to the hundredths place for the mass, so you can have more like $\text{0.0500 M HCl}$.