Understanding Molarity & Molality

Concept #1: The property of any solution depends on both the dissolved solutes and the solution's overall concentration. 

Example #1: A solution is prepared by mixing 20.00 g of CdCl2 (MW of CdCl2 is 183.317 g/mol) with 80.00 g of water has a density at 20 oC of 1.1988 g cm-3.  Compute the molarity of CdCl2 in this solution.

Example #2: In order to sterilize our drinking water, chlorine is routinely added to our water supply. If the water fountains at a park have a chlorine level of 185 ppm calculate the molarity in µM. (MW of Cl = 35.453 g/mol)

Molarity & Molality Calculations

Example #3: A solution is prepared by dissolving 41.33 g nitric acid, HNO3, in enough water to make 100.0 mL of solution. If the density of the solution is 1.380 g/mL, what is the molality of HNO3 in the solution? (MW of HNO3 is 63.018 g/mol). 

Example #4: If the mole fraction of ethanol, CH3CH2OH, in an aqueous solution is 0.090 what is the molality and molarity? Density of the solution is 1.35 g/mL.