Question 990430
Pure "hydrochloric" is a gas.  That would be as Hydrogen Chloride, and not as "hydrochloric acid".  You cannot expect a MIXTURE of the two phases.


Maybe you may expect the pure hydrogen chloride to dissolve into the hydrochloric acid solution to increase the concentration.  You would use (depending on condtions), 22.41 liters per mole of gas.  Work with the concentration quantities in percents, mass, moles, and then use the molar density to find the volume of the gas.


Not finished, obviously.  I would assume your liquid solutions are as mass per volume, and you would solve first for how much mass of HCl is needed; and then convert this into volume of gas to be used, and then involving the formula weight of HCl.  One might assume that addition of the gas has negligible effect on solution volume.