What is the molarity of muriatic acid?

It varies depending on where you buy it since it refers to a commercial grade (impure) solution.

The of muriatic acid depends on where you buy it.

Muriatic acid is an old name for hydrochloric acid. The commercial grade (impure) solution is still sold as muriatic acid. You use it in toilet bowl cleaners, for cleaning masonry, and for adjusting the of swimming pools.

My local hardware store sells muriatic acid labelled as 31.5 % HCl. Its is 1.16 g/mL.

Assume you have 1 L of this muriatic acid (MA).

Moles of HCl = 1000 mL MA ×

##(1.16" g MA")/(1" mL MA") × (31.5" g HCl")/(100" g MA") × (1" mol HCl")/(36.46" g HCl")## = 10.0 mol HCl

Molarity = ##"moles"/"litres" = (10.0" mol")/(1" L")## = 10.0 mol/L

For comparison, pure concentrated hydrochloric acid has a concentration of 37.2 % and a molarity of 12.2 mol/L.