3 replies to this topic

[markymaark]

Ok, quick question.

I am looking at Perry's page 2-85 Table 2-21 for Partial Pressure of H20 over aqueous solutions of NH3

The column description is listed as "Molal concentration of ammonia in the solutions in percentages"

so for my concentration of 180ppm, is that..

0.180/17= .1 mol/L

or molNH3/molH20

seems ambiguous to me

[Steve Hall]

Molal concentration is moles of solute per mass of solvent (in kg).

[markymaark]

Molal concentration is moles of solute per mass of solvent (in kg).

Right, it was the percentage part that added confusion. Thank you

[latexman]

Molality is actually moles of solute/mass of solvent (not mass of solution). Units would be gram-moles/gram. Perry is using % with no units, so I think he is using mole %. You can double-check this by converting one of his molality numbers into a wt % and seeing if it matches the corresponding wt. % he gives.