1. Chapters 15 and 16 Unique properties of water Solution formation
Calculating solution concentration

2. Solution formation how fast can a solute dissolve, and
Three big ideas…
how fast can a solute dissolve, and
how much solute can you dissolve?
How is concentration quantified?

3. Speed of Solvation (dissolving)
What factors determine how fast a solute will dissolve?
Stirring (agitation)
Temperature
Surface area of solute

4. Solubility Quantified
How much can you dissolve?
The solubility of a solute = grams of solute that will dissolve in 100 g of solvent.
There is a limit!
Solubility curves (next slide) show how solubility changes with temperature

5. Solubility Curve 1. For ionic solutes, how does solubility
change with temp?
Units on y-axis are very important.
Saturated, unsaturated, supersaturated – what’s the difference?
Compare to gas solubility.

6. Calculation types Molarity Molality Percent by mass and volume
Freezing and boiling point changes

7. Molarity Molarity = moles of solute liters of solution M = mol L
The most often-used concentration
unit in chemistry

8. 1. 1. 461 g NaCl was dissolved in a 250. 0 mL volumetric flask. Find M
g NaCl was dissolved in a mL volumetric flask. Find M. 2. How many mL of a M NaCl solution are needed to obtain moles of NaCl? 3. You need to make 250 mL of a M Cd(NO3)2 solution. How many grams of Cd(NO3)2 are needed?
M mL g

9. Dilutions Solutions can be made less-concentrated by diluting them.
A pipette, and another volumetric flask, are used for this.
How this problem actually looks in the lab…How many mL of a 0.35 M NaCl solution are needed, to make 500 mL of a M solution?

10. M1V1 = M2V2 Dilution problems are solved by understanding this:
moles taken from original solution = moles present in new solution
M1V1 = M2V2

11. Dilution Problem
How many mL of a 0.35 M NaCl solution are needed, to make 500 mL of a M solution?
57 mL

12. Molality kg of solvent m = mol kg Used in colligative property calcs
Molality = moles of solute
kg of solvent
m = mol kg
Used in colligative property calcs

13. 1. You need a 0. 150 m NaCl solution
1. You need a m NaCl solution. How many grams of NaCl need to be dissolved in 500 g of water? g NaOH are dissolved in 250 g of water. Calculate m.
g m

14. Percent Concentration
% (m/m) = mass of solute x 100
mass of solution
% (v/v) = volume of solute x 100
volume of solution

15. Percent Problems 2. 35 mL of ethyl alcohol dissolved in 55 mL water.
g of KOH dissolved in 45 g water.
2. 35 mL of ethyl alcohol dissolved in 55 mL water.
3. How many mL of H2O2 are in 25 mL of a % H2O2 solution?
% % m mL