A12.34 ml solution with an unknown salt concentration had a mass of 10.25g. when the water was evaporated from the solution 4.78 g of nacl remained. calculate the mass-mass percent nacl concentration in the solution.

46.6% The m/m percentage is the percentage of solute mass per mass of total solution. For instance, 100 grams of solution with 1 gram of solute would be a 1% solution. So all we need to do is divide the mass of NaCl by the original mass of the solution to the the percentage m/m of that solution. So 4.78 g / 10.25 g = 0.466341463 = 46.6341463% Rounding to 3 significant figures gives 46.6% This is a remarkably high concentration of NaCL since at 25C, one can dissolve 359 grams into 1 liter of water. So the most that should be in 12.34 mL is 4.43 grams of NaCl. But that's neither here, nor there are regards this problem.