1. Solutions

2. Definitions Solute - substance being dissolved
Solvent – substance that is doing the dissolving (usually present in greater amounts)
Solution – a mixture of substances that has uniform composition (homogenous mixture)

3. Solutions: Basic Definitions
Soluble – when a substance will dissolve in another substance
Ex: salt and water
Insoluble – when a substance will not dissolve in another substance
Ex: sand & water

4. Solutions: Basic Definitions
Miscible – when two liquids are soluble in each other
Ex: alcohol & water
Immiscible – when two liquids are not soluble in each other
Ex: oil & water
Aqueous – a solid dissolved in water

5. Solutions: Basic Definitions
Electrolyte – a solution that separates into charged particles that conducts an electric current
Non electrolyte – solution that separates into charged particles that does not conduct an electric current

6. Solvation
“Like Dissolves Like”
NONPOLAR
POLAR

7. Polar vs. nonpolar?
Molecules may be polar or non‐polar depending on the types of bonds and the arrangement of the bonds, that is, the shape of the molecule.
In general:
Polar – unequal distribution of electrons
Ionic Compounds = Polar
EX: Water is the universal solvent for polar compounds
Nonpolar – equal distribution of electrons
Covalent Compounds = Nonpolar
***Remember the phrase “LIKE DISSOLVES LIKE”

8. Increasing the Rate of Solution
Agitation
If you increase the speed of the particles, you increase the dissolving process
Increasing Temperature
As you increase the temperature, more particles will collide (high KE), thus increasing the rate of reaction
Increasing Surface Area
Smaller particles dissolve faster than larger particles due to an increased surface area
Which will dissolve faster: Sugar cube vs. Teaspoon of sugar?

9. Solubility Solubility
Maximum grams of solute that will dissolve in 100 g of solvent at a given temperature
Varies with temperature
Based on a saturated solution

10. Solutions: Basic Definitions
unsaturated solution - If the amount of solute dissolved is less than the maximum that could be dissolved (point below the line)
saturated solution - solution which holds the maximum amount of solute per amount of the solution under the given conditions (point on the line)
supersaturated solution - solutions that contain more solute than the usual maximum amount and are unstable (point above the line)
Which solution allows for more solute to be added?

11. Solubility UNSATURATED SOLUTION more solute dissolves
no more solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration

12. Solubility Graph Solubility Curve
Shows the dependence of solubility on temperature
Factors that affect a substance’s solubility:
Amount of solute (in grams)
Amount of solvent (in grams)
Specified temperature (in °C)

13. 79 81 Unsaturated KNO3 KCl NaCl To read the graph:
Look for the given information first.
Read up or over until you hit the line for your compound.
Go to the other axis for the information you are looking for.
Exa: How many grams of KNO3 will dissolve in 100 g of H2O at 50C? _______ g
Exb: At what temperature will 52 grams of KCl dissolve in 100 g of H2O?
_______ C
Exc: What kind of solution would you have if you dissolved 10 g of KCl in
100 g H2O of at 0  C?
Unsaturated
KNO3
KCl
NaCl 79 81

14. Calculating from the Graph
Sometimes a question can be asked that cannot be answered solely from reading the graph. But information can be obtained from the graph to help answer the question.
Find the maximum amount of NaCl that will dissolve at the given temperature.
Subtract the given amount from the maximum amount.
Exa: Dissolving 25 g of NaCl in 100 g of H2O at 75 °C produces an unsaturated solution. How many more grams of NaCl must be added to saturate the solution?
40 g – 25 g = 15 g needed
KNO3
KCl
NaCl

15. Exb: What is the minimum mass (in grams) of 90 °C water needed to dissolve 70 grams of KCl?
Find the maximum amount of KCl that will dissolve at the given temp. ______ g
Set up an inequality that shows the info you have at that temp
on the left, write what you see on the graph
on the right, write what you want to do.
Cross multiply to solve for X
KNO3
KCl
NaCl 55
55 g KCl =
100 g H2O
70 g KCl
X g H2O

16. Reading Solubility Graphs