1. Solutions

2. Components of Solutions
Component: a substance that is part of the solution
Solvent: present in the greatest amount
Solute: other than solvent (lower amount)

3. Mixtures that are not Solutions
There are 3 types of mixtures: solutions, colloids and suspensions
Solutions are homogeneous with small particles and thus show no Tyndall effect
Colloids – appears to be a homogeneous mixture, but particles are much bigger, but not filterable. E.g. Fog, smoke, whipped cream, mayonnaise, etc., shows Tyndall effect
Suspension: larger particle sizes, filterable. E.g. mud, freshly squeezed orange juice.

4. Colloids
Tyndall effect: ability of a Colloid to scatter light. The beam of light can be seen through the colloid.

5. Solubility and Solutions
Solubility: Amount of solute that dissolves in a solvent to produce a saturated solution. (Solubility often expressed in g/100 mL.)
E.g g of I2 dissolved in 1000 g of H2O.
Saturated solution: maximum amount of solute is dissolved in solvent. Trying to dissolve more results in undissolved solute in container.

6. Unsaturated solution: less than max
Unsaturated solution: less than max. amount of solute is dissolved in solvent.
Supersaturation = more solute in solution than normally allowed; we call this a supersaturated solution.

7. Factors Affecting Solubility
Polar liquids tend to dissolve in polar solvents due to dipole-dipole and H-bonding interactions

8. Factors Affecting Solubility
Polar liquids tend to dissolve in polar solvents due to dipole-dipole and H-bonding interactions
CH3CCH3
acetone || O
CH3CH2OH
ethanol
Miscible: soluble in all proportions (liquids)
Immiscible: do not dissolve in one another

9. Salt Dissolving in Water

10. Factors Affecting Solubility
Nonpolar liquids tend to be insoluble in polar liquids; e.g. hexane (C6H14) does not dissolve in water. Increasing the nonpolar character of a substance will decrease its solubility in water.

11. Solubility: Temperature Dependence
All solubilities are temperature dependent;
Most solids are more soluble at higher temperatures.
All gases are less soluble at higher temperatures.

12. Factors Affecting Solubility
Temperature Effects

13. Factors Affecting Solubility
Temperature Effects
How many grams of sodium nitrate can dissolve in 50g of 10oC water?
If 39g of sodium nitrate is dissolved in 50 g of 10oC water, what type of solution is it? 41g?
Which solute shows a decrease of solubility with an increase in temperature?
If a saturated potassium nitrate solution is prepared at 20oC, how much more salt can be added if the temperature is increased to 50oC?
How can you make a supersaturated solution?

14. Factors Affecting Solubility
Temperature Effects

15. Ways of Expressing Concentration
Concentration: intensive property that conveys the amount of solute relative to the amount of either solvent or solution
Qualitative ways: Dilute
Concentrated
Quantitative ways: Numeric representation
Several ways

16. Units of Concentration
Molarity
Weight (mass) Percent (wt%)(m/m%)
parts per million (ppm) and parts per billion (ppb) for small concentrations.
Notice that the denominator is solution not solvent so it is the sum of the solute and solvent

17. Units of Concentration
Volume Percent (v/v%)
Mass/Volume percent. (m/v%)
Notice that the denominator is solution not solvent so it is the sum of the solute and solvent

18. Molarity Convenient way to prepare solution in lab
1-L flask ( mL)
Convenient way to prepare solution in lab
add 0.5 mol solute
dilute to mark
get 0.5 M solution

19. Example
How many grams of sulfur Hydride (H2S) must be dissolved in 1L of water to make a 0.12 M solution?

20. Example
How many grams of sulfur Hydride (H2S) must be dissolved in 1L of water to make a 0.12 M (0.12 mols/L) solution?
1.0L x 0.12 mol x ( ) g =
L 1mol
Dissolve in enough water to make 1 litre

21. Parts per Million (ppm) and Parts per Billion (ppb)
= = 0.25 part per part

22. ppm and ppb practise
If you dissolve 0.05 g of sodium chloride in 1 L of water, what is the ppm concentration of sodium ions?
1L of water is 1000mL and thus 1000g (density of water is 1g/mL)
Mass of solute/mass of solution x 1 million
O.05/( ) x 1million= 50ppm
If you find 0.4mg of lead in a beluga whale weighing 245kg what is the concentration of lead in ppb?
0.0004g/245000g x 1billion= 1.6ppb

23. Mass percentage
e.g. Solution of HCl that is 36% by mass contains 36 g of HCl for every 100 g solution
Both the solute and solution need to be measured in the same units.

24. Mass percent practise
If a solution of vinegar is 5.0 % m/m by mass and the container of vinegar is 275g, how much acetic acid is present in the container?
275 g x 5/100= g of acetic acid

25. Volume Percent and Mass/Volume Percent
Concentration can also be calculated using volume percent and mass/volume percent.
Volume percent is the ratio of volume of solute to the volume of solution times The volume of both have to be in the same units so the units cancel. (v/v%)
Mass volume is the ratio of the mass of solute in grams divided by the volume of solution in mL times (m/V%)
Mass/volume is more specific in the requirement of the units of measure for the solute and solution.

26. Volume percent and mass/volume percent practise
If you mix 2.0mL of HCl with 20.0 mL of water what is the volume percent of acid?
2.0mL/(2 +20)mL x 100 = 9.1 % v/v
If you mix 5g of sodium chloride with a little bit of water and then add enough water so that the solution is 20 mL, what is the mass/volume concentration?
5g/20mL x100= 25% m/v