1. Solubility of Solids, Solubility of Gases and Solution Concentration

2. T↑ S↑ Solubility of Solids
Solubility is the maximum amount of a substance that will dissolve in a certain quantity of water at a specific temperature
Solubility of solids is temperature dependent
For solids:
In other words, as the temperature goes up, so does the solubility.
T↑ S↑

3. Solubility of Solids Factors that affect dissolving rate:
Surface area of crystal
Stirring/Agitation
These only affect the rate at which a solute will dissolve, it does not influence the amount that will dissolve.
Temperature affects both the rate and the amount that will dissolve
Temperature affects different solutes differently

4. Solubility of Solids Types of Solutions
Saturated – the maximum amount of a solute dissolved in a given amount of water at a certain temperature
Unsaturated – less than the maximum amount of a solute dissolved at a certain temperature
Supersaturated – more than the maximum amount of a solute dissolved at a certain temperature
Occurs when a solution is heated, solute is added and then allowed to cool down ex: rock candy

5. Solubility Graph Any point on the line is saturated
Any point above the line is supersaturated
Any point below the line is unsaturated

6. Solubility Graph
What amount of KNO3 will dissolve at 50°C?
80 grams •

7. Solubility Graph
If 60 grams of KNO3 were dissolved at 80°C, what type of solution would be made?
unsaturated •

8. Solubility Graph
If 60 grams of KNO3 were dissolved at 30°C, what type of solution would be made?
supersaturated •

9. Solubility Graph
If 60 grams of KNO3 were put in a solution at 30°C, what type of solution would be made?
saturated
Think about putting sugar in cereal

10. Dissolving Ionic Compounds
Dissolving is like a tug of war
Solids will dissolve if strongly attracted to water
molecules
To dissolve, the attractive forces between ions must be overcome
Dissolving occurs at the surface of the crystal 10

11. Dissolving Ionic Compounds
The water molecule is attracted to the ions
“Like dissolves Like”
Polar will dissolve polar and ionic 11

12. Dissolving Ionic Compounds12

13. T↑ S↓ Solubility of Gases The solubility of gases is quite different
For gases:
So, for gases, as the temperature goes up, the solubility goes down
Think about an opened pop or one that gets warmer
T↑ S↓ 13

14. Solubility of Gases
Please notice that the solubility of gases is far less soluble in water than solids

15. Solubility of Gases
The solubility of gases is directly proportional to the gas pressure on the liquid
If the pressure doubles, the amount of gas dissolved would double
Open up a pop – what happens?
The pop will “go flat” even though there is still CO2 in the pop
The pressure of CO2 in the pop will try to equal the atmospheric pressure of CO2

16. Solution Concentration
Solution Concentration is the quantity of solute dissolved in a quantity of solution (solute + solvent)
What is the concentration of a solution made from 20 g of sugar in 80 g of water?
g of solute
× 100
g of solution
20 g sugar
× 100 = 20%
100 g solution

17. Solution Concentration
Some common concentration units:
pph – parts per hundred (also referred to as percent)
ppt – parts per thousand
ppm – parts per million
ppb – parts per billion

18. Solution Concentration
A 5% (pph) salt solution is how many ppm?
Cross multiply and divide : 5 × ÷ 100 and you should get an answer of 50,000 ppm 5 X =
100

19. Oxygen – Supply and Demand
All animals need oxygen gas (O2) to survive
Aquatic organisms need a continuous supply of dissolved oxygen (DO)
Ways that oxygen gets into water
Dissolved directly from the air above the water
Aeration
Photosynthesis

20. Aeration
Aeration – air is forced into water by a dam, by rapids in a river or stream or by the waves on a beach

21. Photosynthesis
Photosynthesis – the production of oxygen by green plants through a chemical reaction
Energy(sun) + 6 CO2 + 6 H2O → C6H12O6 + 6 O2

22. Oxygen – Supply and Demand
Aerobic Bacteria, oxygen consuming bacteria, also need oxygen to survive
Live off of biodegradable substances which they break down
More biodegradable substances = more aerobic bacteria
More aerobic bacteria = greater struggle for fish

23. Oxygen – Supply and Demand
Most fish require a minimum of 4 ppm (0.004 g/1L) of DO
Less than that and fish will either migrate or die

24. Bibliography