1. Chapter 7.2 & 7.3: Solutions from 7.1, In a solution
solute: stuff dissolved
solvent: it’s dissolved in
Called the universal solvent, because almost almost everything dissolves in water (not because our bodies are mostly water or the Earth is 75% water)
Water
Polar compound: oxygen keeps the electrons a little more than hydrogen does, so it has a little bit of charge on each end
“uneven distribution of electrons” … not equally shared, so has charge

2. Dissolving Process
in water, the partial charge helps pull molecules apart, making more room for interactions between molecules
breaking apart gives more surface area for interactions between molecules
stirring/shaking moves molecules away, making more room for interactions between molecules
heating makes molecules move faster so there’re more interactions between molecules

3. Hydrogen Bonding
Because water is polar, it forms hydrogen bonds between atoms
Not a bond within one molecule, e.g. between the hydrogen and oxygen
A bond between 2 atoms…hydrogen of 1 water is attracted to oxygen of another because water is polar .

4. Nonpolar compounds no partial charges
“electrons evenly distributed” … evenly spread out, so no charges
e.g. oil
Like Dissolves Like:
Things only dissolve in similar solvents, i.e. polar in polar and nonpolar in nonpolar.

5. Solubility and Concentration
Solubility: maximum amount of solute that will dissolve at a particular temperature and pressure (quantitatively)
also how well it dissolves in something (qualitatively)
depends on the strength of attraction between atoms
g solute/100mL solvent (1 mL isn’t a lot, so we use 100 mL)
Concentration: actual amount dissolved
g solute/mL solvent (similar to density, but 2 substances)
a lot: concentrated
a little: dilute

6. Concentrations of solutions
unsaturated: can hold more solute, holding less than the maximum amount at that temp.
saturated: can not hold any more, holding the maximum amount at that temp.
supersaturated: hold more than normal at that temp (make by heating, adding solute and then cooling)
video:

7. Factors affecting solubility
Temperature: as temp of solvent goes up, can hold more solid, but less gas
Pressure: as pressure goes up, can hold more gas
So…to dissolve more solid, increase temperature
To dissolve more gas, increase pressure

8. Solubility Curves show how much will dissolve at a certain temperature
If you have a concentration on the line, it is saturated. It is holding the maximum it can at that temp

9. Solubility Curves
If you have a concentration above the line, it either will not stay in solution, because it is holding more than the maximum it can at that temp. Or it will be supersaturated.
If you have a concentration below the line, it is unsaturated. It is holding less than the maximum it can at that temp … you can still add more solute.

10. Solubility Curves
Note how the line for a gas looks different … as temp goes up, the gas molecules move faster and do not stay in the solution.
Sol. decreases as temp. increases