# What is the molar concentration of "78% w/w" HCl(aq)?

The concentrated $H C l$ solution supplied to laboratories is 38% (w/w), with $\rho$ $=$ $1.189 \cdot g \cdot m {L}^{-} 1$. This corresponds to a molarity of approx. $12$ $m o l \cdot {L}^{-} 1$. I imagine stronger concentrations than this would have to be made under $H C l \left(g\right)$ atmospheres.