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what is water
It is a Polar Molecule with one positive end (hydrogen) and one negative end (oxygen)
why is water the most effective solvent?
because it is highly polar
what can water dissolve
ionic and polar compounds (water cannot dissolve nonpolar compounds)
what does water’s polarity mean
it has a positive and negative end
example of dissolving water and salt
When mixed with salt, NaCl, water’s negative end (oxygen) is attracted to NaCl’s positive end (Na)
Water’s positive end (hydrogen) is then attracted to NaCl’s negative end (Cl)
Solubility
The ability to dissolve a solute in a solvent to form a solution, a homogeneous mixture
Solute
The matter dissolved in a solvent
solvent
The matter in which a solute is dissolved
solution
Homogeneous mixture
Aqueous Solutions
solution where water is the solvent
what is solubility heavily based upon
polarity!
“like dissolves like”
means that substances with the same polarity dissolve each other
Ionic compounds dissolve in
polar solvents
Polar compounds dissolve in
polar solvents
Non-polar compounds dissolve in
nonpolar solvents
why dont water and oil mix
oil is nonpolar, water is polar
what are the factors affecting solubility
temperature and pressure
As temperature ↑, solubility of liquids and solids
↑
As temperature ↑, solubility of gases
↓
As pressure ↑, solubility of liquids and solids is
unaffected
As pressure ↑, solubility of gases
↑ (in a liquid)
think about a soda bottle being the fizziest the moment you open it
Dissolution Rate
It’s the rate at which the solute dissolves in the solvent
kinetic energy affecting dissolution rate
As kinetic energy increases, so does the dissolving rate
The opposite is true too!
collisions affecting dissolution rate
As the number of collisions increases, so does the dissolving rate
The opposite is true too!
Temperature is a measure of
kinetic energy
By increasing the heat, the kinetic energy goes up and so does the
speed of the particles
More speed =
more collisions
Breaking a solid into smaller pieces greatly increases
its surface area
More surface area =
smaller particles
Rate of collisions increases as surface area
increases
Agitation is
applying a force to create motion between the solute and solvents
does agitation increase the chance of collisions?
yes!
As the solvent moves around, more collisions occur between solvent and solute particles
3 ways to dissolve solid solute faster
More Agitation
Increasing Surface Area
Increasing Temperature
2 ways to dissolve gases faster
More Pressure
Lower Temperatures
above the solubility line is
supersaturation
below the solubility line is
unsaturated
on the solubility line is
saturated
Saturated Solutions
Containing the maximum amount of dissolved solute that the solution can hold. It is the curve of the graph
no more solute dissolves
Unsaturated Solutions
Contain less dissolved solute and can dissolve more solutes! It is underneath the curve of the graph
Supersaturated Solutions
Contain more dissolved solute than the saturated solution can dissolved. It is above the graph of the curve
becomes unstable, crystals form
key things to know about solubility curves
grams of solute vs temperature
multiple lines
lines rep diff substances
solubility is typically based on 100g of water
What is Concentration?
a measure of how much solute dissolved in a specific amount of solvent or solution
The higher the concentration..
the more solute within the solution
dilution is the ___ of concentration
opposite (think of it like a timeline)
molarity
measure of concentration
moles of solute per liter of solution
molarity misconception
Molarity measures the moles of the solute per 1 liter always. So if you see 12M, that is 12 moles of the solute per 1 liter (12 moles / 1 liter)
molarity equation
m=(n/L)
What does it mean to dilute a solution?
Solutions can be diluted simply by adding water and leaving the amount of solute unchanged
What happens to molarity when a solution is diluted?
More water has been added, so the total volume of solution is greater but the amount of solute is the same
Molarity will decrease!
do number of moles change when diluting a concentration?
no, only volume and molarity
How to Measure out Dilutions
m1v1=m2v2
stock solution
The initial molarity and volume
diluted solution
final molarity and volume
The initial molarity tends to be ____ than the final molarity
bigger
the initial volume tends to be ____ than the final volume.
smaller
Intermolecular forces
Attractive forces between molecules that are weaker than bonds
what do intermolecular forces do
make individual molecules stick together and limits their motion
types of IMF from weakest to strongest
london dispersion forces, dipole-dipole forces, hydrogen bonds, ion-dipole forces
type of imf depends on..
polarity! determine if the bonds are polar or nonpolar
if the electron cloud is shared equally it is
nonpolar (en<.3)
if the electron cloud is shared unequally it is
polar! (en>.3)
dipole
slight pos and neg charges on the ends of the molecule
positive dipole means
less electronegative atom
negative dipole means
more electronegative atom
Nonpolar molecules
no normal charges or dipoles ( small ENÂ difference)
london dispersion forces/vanderwaals
very weak attractive forces between
nonpolar molecules
-normally nonpolar molecules
-temporary dipoles
-attract and stick together
dipole-dipole forces
-polar covalent
-polar molecules - unequal sharing of electron cloud (permanent dipoles)
more polar molecules=
stronger dipole-dipole force
hydrogen bonds
like dipole-dipole except must have H bonded to the highly EN elements
what gives water many of its properties
strong hydrogen bonds between water molecules
What Are Colligative Properties?
the properties of a solvent that change due to the presence of a solute
-It also depends on the concentration of solute particles
whats the point of colligative properties
By adding a solute to the solvent (like salt to water), the properties of your solvent (water) might change
colligative property examples
freezing point depression, boiling point elevation, osmotic pressure, vapor pressure
osmotic pressure
Osmotic pressure varies depending on the solute being added
vapor pressure lowering
The pressure exerted by the gas of the solution is lower
what are electrolytes
solutions that conduct electricity due to dissolved ions caused by dissociation of ionic compounds
can electrolytes vary in strength
yes
Nonelectrolytes do not
conduct electricity
why is salt an electrolyte when dissolved in wate
salt dissociates into sodium and chlorine ions, allowing electricity to flow through it
how to determine if its an electrolyte
has a solute that is an ionic compound (dissolves in water) (check the solubility chart)
When ionic compounds dissolve, in water..
they dissociate (meaning they break down into ions)
nonelectrolytes either
contain polar covalent compounds
have ionic compounds that do not dissolve
strong electrolytes are
strong Acids
Strong Bases
Ionic Compounds
Weak electrolytes are…
-weak acids
-weak bases
Note 
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