Containers 1, 2, and 3 all hold 100.00 mL of 1.0 M solutions. One solution is sodium hydroxide, NaOH; another is sodium bromide, NaBr; and the third is potassium chloride, KCl.

Question

Container 1 has a mass of 194.10 g, container 2 has a mass of 196.83 g, and container 3 has a mass of 192.65 g. Which solution is in which container.

Answer 1

Since all solutions contain 0.1 mol of the substance in 0.1 liter of solution (1.0 M), we should need only find the mass of 0.1 mol of NaOH, NaBr and KCl. The volume of water will ~ the same (~ 100 g for 100.00 ml).

mass of 0.1 mol NaOH = 40.1 g/ mol x 0.1 mol = 4.1 g + 104.1 g H2O = 104 g

mass of 0.1 mol NaBr = 102.89 g / mol x 0.1 mol = 10.3 g + 100 g H2O = 110.3 g

mass of 0.1 mol KCl = 74.6 g / mol x 0.1 mol = 7.46 g + 100 g H2O = 107.5 g

When you provide the mass of container 1, 2 and 3 as 194.1 g, 196.83 g and 192.65 g respectively, are those the masses of the containers alone, or with the solution? One must assume it is the container PLUS the solution, but then we'd need to know the mass of each individual EMPTY container, so we can subtract that from the calculated masses above. Not sure that this question can be answered as written, without knowing the density of the the three different solutions.

Without any additional information, and based only on mass of solution, it would appear that

container 3 has NaCl

container 1 has KCl

container 2 has NaBr