1. The problem statement, all variables and given/known data 0.1004g of PbS, 14 mL of HCl, 3mL HNO3 are put in a 100mL volumetric flask, with deionized water filling up the remainder of the volume up to the mark. 5mL of this solution is added to a 250mL vol. flask in addition to 0.3g NaCl, 2.5g HCl, and deionized water filling up the remainder of the volume up to the mark. What is the total mass of the 250mL solution? 2. Relevant equations N/A 3. The attempt at a solution I don't know the volume nor mass of deionized water used in either instance. Don't molecules of certain fluids "blend into each other," taking up less than their respective volumes would have you believe? Mass is conserved, however, of course. The only way I can think of doing this, with the information given, is to assume that the solutions have a density equal to that of water, but that is a simplification (though there isn't much of anything in either solution, so I'd guess the true density isn't far off). Any thoughts?