DENSITY

[geolix]

hcl has a density of 1.49 hno3 has a density of 1.42
when these two solvent is use to dissolve a solute ,the density of the solution changes.Is there any difference in the concentration of the solute if the solution is made up to 100 ml flask or 100g which is equivalent to 90 ml in a 100 ml flask.

[tom jupille]

Depends on the units you are using for concentration. The best is something (relatively) unequivocal like mg/mL (mg of solute / mL of solution). Using % is more ambiguous but even that isn't too bad if you specify w/w or w/v. PPM is horrible because people usually *don't* specify w/w or w/v.

[Peter Apps]

Since you have a (presumably) fixed amount of solute dissolved in either 100g (90ml) or (approx) 110 g (100 ml) then by any measure the concentration or volume fraction or mass fraction will be different in one than in the other. And, as Tom says you must be careful, and explicit, about what units you are using.

Peter