chapter 12: solutions
formation of solutions!
dissolution: (dissolving) each solute particle is completely surrounded by solvent (h2o) particles
solute: soluble covalent compounds or ionics
to dissolve in water → polar
dissociation: soluble, ionic compounds separate into ions (electrolytes, conductive*)
when dissolved!
three ways to dissolve a solid more quickly!
stir: (shake, agitate)
solute comes in contact with solvent more often
decrease particle size: (grind)
solute dissolves faster with more surface area
heat:
particles moving aster more forceful collisions
heat increases solubility of solids
solubility[mass (or number of mols) of solute / volume of solution/solvent]
factors affecting solubility
temperature
solids dissolve better in warmer temperatures
gases dissolve better in cooler temperatures
pressure
solids dissolve easily in lower pressures
gases dissolve easily in higher pressures
this is HENRY’S LAW
saturation
**use solubility chart/curve
saturated: solution where is has the max amount of solute at a particular temperature
(on line)
unsaturated: solution with less than the max amount of solute
(under the line)
supersaturated: solution with more than the maximum amount of solute
(above the line)
increase temperature so you can dissolve more and then cool it back down
created by
dissolve solute in warm solution, cool slowly (solid stays dissolved)
destroyed by
adding seed crystal (small piece of original solute)
stirring or shaking
difference between supersaturated solution and max amount of solution is what precipitates out
left with → solid → saturated solution** (check this)*
concentration
expresses how much solute is dissolved in solvent
concentrated: lots of solute
dilute solution: only a little solute, compared to solvent
molarity (M)
moles of solute (n) per liter of solution (V)
M = (n/v) = (moles solute/liters of solution)
**dependent on temperature because volume of solution would change slightly
molality (cursive small ‘m‘)
moles solute per kilogram of solvent
m = (moles of solute / kg of solvent)
**not dependent on temperature!
parts per million (ppm) and parts per billion (ppb)
used for expressing very small concentrations, particularly for containments in environment
ppm = [ mass of solute (g) / vol of solution (mL)] * 10^6 (million)
ppb = [mass of solute (g) / vol of solution (mL)] * 10^9 (billion)
<strong>dilution</strong>
a dilute solute can be made by adding more solvent to a concentrated solution
amount of solute stays the same
serial dilution!
colligative properties
show how solutions behave differently than pure solvents
depends of number of solute particles in solution, not type
changes are more extreme when solutions are concentrated (more particles) rather than dilute
lower vapor pressure
solute particles inhibit solvent from escaping as gas
less gas → less pressure
boiling point elevation
solute particles make it more difficult for solvent to escape as gas
more energy needs to escape → higher temperature to boil
determining ΔBP: ΔT = (i)(Kb)(m)
ΔBP - change in temperature, not new boiling point
i - # of disassociated particles
VAN’T HOFF FACTOR
i for all molecular compounds equals one!!
Kb - boiling constant, unique for each constant
m - molality: moles solute/kg solven
freezing point depression
solute particles prevent pure solvent from forming
cold temp needed to form solid
determining ΔFP: ΔT = (i)(Kf)(m)
ΔT - change in freezing point
i - # of particles
Kf - freezing constant
m - molality
osmotic pressure
osmosis: the movement of H2O through semi-permeable membrane
increases as the difference in concentration increases
* applying force to stop water from moving across the membrane
force is known as osmotic pressure
formation of solutions!
dissolution: (dissolving) each solute particle is completely surrounded by solvent (h2o) particles
solute: soluble covalent compounds or ionics
to dissolve in water → polar
dissociation: soluble, ionic compounds separate into ions (electrolytes, conductive*)
when dissolved!
three ways to dissolve a solid more quickly!
stir: (shake, agitate)
solute comes in contact with solvent more often
decrease particle size: (grind)
solute dissolves faster with more surface area
heat:
particles moving aster more forceful collisions
heat increases solubility of solids
solubility[mass (or number of mols) of solute / volume of solution/solvent]
factors affecting solubility
temperature
solids dissolve better in warmer temperatures
gases dissolve better in cooler temperatures
pressure
solids dissolve easily in lower pressures
gases dissolve easily in higher pressures
this is HENRY’S LAW
saturation
**use solubility chart/curve
saturated: solution where is has the max amount of solute at a particular temperature
(on line)
unsaturated: solution with less than the max amount of solute
(under the line)
supersaturated: solution with more than the maximum amount of solute
(above the line)
increase temperature so you can dissolve more and then cool it back down
created by
dissolve solute in warm solution, cool slowly (solid stays dissolved)
destroyed by
adding seed crystal (small piece of original solute)
stirring or shaking
difference between supersaturated solution and max amount of solution is what precipitates out
left with → solid → saturated solution** (check this)*
concentration
expresses how much solute is dissolved in solvent
concentrated: lots of solute
dilute solution: only a little solute, compared to solvent
molarity (M)
moles of solute (n) per liter of solution (V)
M = (n/v) = (moles solute/liters of solution)
**dependent on temperature because volume of solution would change slightly
molality (cursive small ‘m‘)
moles solute per kilogram of solvent
m = (moles of solute / kg of solvent)
**not dependent on temperature!
parts per million (ppm) and parts per billion (ppb)
used for expressing very small concentrations, particularly for containments in environment
ppm = [ mass of solute (g) / vol of solution (mL)] * 10^6 (million)
ppb = [mass of solute (g) / vol of solution (mL)] * 10^9 (billion)
<strong>dilution</strong>
a dilute solute can be made by adding more solvent to a concentrated solution
amount of solute stays the same
serial dilution!
colligative properties
show how solutions behave differently than pure solvents
depends of number of solute particles in solution, not type
changes are more extreme when solutions are concentrated (more particles) rather than dilute
lower vapor pressure
solute particles inhibit solvent from escaping as gas
less gas → less pressure
boiling point elevation
solute particles make it more difficult for solvent to escape as gas
more energy needs to escape → higher temperature to boil
determining ΔBP: ΔT = (i)(Kb)(m)
ΔBP - change in temperature, not new boiling point
i - # of disassociated particles
VAN’T HOFF FACTOR
i for all molecular compounds equals one!!
Kb - boiling constant, unique for each constant
m - molality: moles solute/kg solven
freezing point depression
solute particles prevent pure solvent from forming
cold temp needed to form solid
determining ΔFP: ΔT = (i)(Kf)(m)
ΔT - change in freezing point
i - # of particles
Kf - freezing constant
m - molality
osmotic pressure
osmosis: the movement of H2O through semi-permeable membrane
increases as the difference in concentration increases
* applying force to stop water from moving across the membrane
force is known as osmotic pressure