Untitled - Kelly Walsh High School

174 CHEMISTRY FOR THE UTTERLY CONFUSED
Don’t Forget!
A solution is prepared by mixing 125.0 g of benzene in enough toluene to yielding
a solution whose volume is 326.3 mL. Determine the mass/volume percentage
of the solution.
Mass/Volume %
(125.0 g benzene)
(326.3 mL solution)
100% 38.31 %
If the volumes of both the solute and solvent are given, don’t forget to add both
volumes together to give the volume of the solution.
Volume/volume Percentage
The third case is one in which both the solute and solvent are liquids. The volume
percent of the solution is the volume of the solute divided by total volume
of the solution and then again multiplied by 100% to generate the percentage.
Volume % (volume solute/volume solution) 100%
Determine the volume percentage of carbon tetrachloride in a solution prepared
by dissolving 100.0 mL of carbon tetrachloride and 100.0 mL of methylene chloride
in 750.0 mL of chloroform. Assume the volumes are additive.
Answer:
Volume%
(100.0 mL carbon tetrachloride)
(100.0 100.0 750.0) mL solution
Molarity
While percentage concentration is common in everyday life, most chemists
(and chemistry students) use molarity. Molarity (M) is the number of moles of
solute per liter of solution:
M moles solute/liter solution
Refer back to Chapter 4 for problems related to molarity.
100% 10.53%