Practice: A solution is prepared by dissolving 43.0 g potassium chlorate, KClO3, in enough water to make 100.0 mL of solution. If the density of the solution is 1.760 g/mL, what is the molality of KClO3 in the solution?
Molality (m) represents the number of moles of solute dissolved per kilogram of solvent.
Concept #1: Molality
Example #1: A solution contains 24.8 g of sucrose (C12H22O11) dissolved in a 550.0 g of water. Calculate the molality of the solution.
Practice: A solution is prepared by dissolving 43.0 g potassium chlorate, KClO3, in enough water to make 100.0 mL of solution. If the density of the solution is 1.760 g/mL, what is the molality of KClO3 in the solution?
Practice: The density of a 15.7 M methanol (CH3OH) solution is 0.858 g/mL. If H2O is the solvent, what is the molality of the solution?
Concept #2: Osmolality
Osmolality or Ionic Molality, represents number of dissolved particles in a solution.
Example #2: What is the osmolality of total ions in an aqueous solution prepared by dissolving 0.400 moles of Pb(NO3)4 in 750.0 g water?
Practice: What is the ionic molality of sodium ions in a solution of 25.7 g NaNO3 dissolved in enough water to make a 150.0 mL of solution? Density of the solution is 1.02 g/mL.