This site gives me the following data with respect to conc. HCl: ρ=1.17⋅g⋅mL−1; concentration=36.5%(ww).
We want Moles of HClVolume of solution (L) to assess the molar concentration. And so.....we assume a 1⋅mL volume of stuff:
1.17⋅g×36.5%36.46⋅g⋅mol−11×10−3⋅L=11.7⋅mol⋅L−1
We want a 1⋅L volume of 1⋅mol⋅L−1 HCl, i.e. we want a 1⋅mol quantity of HCl.
And so we take a 85.5⋅mL volume of conc. HCl, and we add this to approx. 900⋅mL of water in a volumetric flask. The order of addition is ALWAYS acid to water. Why? Because if you spit in conc. acid it spits back, I kid you not! After the initial dilution we can make this up to 1⋅L.
And so concentration = Moles of HClVolume of solution
=85.5×10−3⋅L×11.7⋅mol⋅L−11⋅L=1.00⋅mol⋅L−1.
