Solutions Flashcards
solution
homogenous mixture of two or more compounds in a single phase
solvent vs. solute
solvent = compound of which there is more
solute = less of
(both can be referred to as solvents)
general rule for dissolution
like dissolved like
-refers to polarity of solute and solvent
London dispersion forces
- highly polar molecules held together by strong molecular bonds formed by attraction between their partially charged ends
- nonpolar molecule held together by weak intermolecular bonds from instantaneous dipole moments
ionic compounds dissolved by ___
polar substances
solvation
ionic compounds break apart into cations and anions and are surrounded by the oppositely charged ends of the polar solvent
____ is good solvent for ionic substances
water
hydration
using water as a solvent…when several water molecules attach to one side of ionic compound, they can overcome ionic bonds and break apart compound, molecules surround ion
aqueous phase
something that is hydrated
electrolyte
compound that forms ions in aqueous solution, create solutions that conduct electricity
NO2(-)
nitrite
NO3(-)
nitrate
SO3(2-)
sulfite
SO4(2-)
sulfate
ClO(-)
hypochlorite
ClO2(-)
chlorite
ClO3(-)
chlorate
ClO4(-)
perchlorate
CO3(2-)
carbonate
HCO3(-)
bicarbonate
PO4(3-)
phosphate
Molarity
moles of the compound divided by the volume of the solution (mol/L)
molality
moles of solute divided by kilograms of solvent (mol/kg).
mole fraction
moles of a compound divided by total moles of all species in solution
mass percentage
100 times the ratio of the mass of the solute to the total mass of the solution
parts per million (ppm)
10^6 times the ratio of the mass of the solute to the total mass of the solution
solution formation and heat of solution
step 1: breaking bonds of solute, endothermic, +delta H1
step 2: braking bonds of solvent, endothermic, +delta H2
step 3: formation of bonds between solvent and solute, exothermic, -delta H3
heat of solution = delta H1 + delta H2 + delta H3 ; overall change in energy of the reaction is equal to the change in enthalpy
negative heat of solution
stronger intermolecular bonds, lower vapor pressure
positive heat of solution
weaker intermolecular bonds, raise vapor pressure
formation of solution usually involves ___ in entropy
increase in entropy….combined mixture is more disordered than the separated pure substances
when gas dissolves in liquid or solid, entropy change is…
negative
one condensed phase (liquid or solid) dissolving into another, ___ in entropy
increase
vapor pressure
partial pressure of the compound necessary to create equilibrium between the liquid and gas phases of a compound
vapor pressure is function of ___
temperature, increases with temp
evaporates when…
vapor pressure of liquid phase is greater than partial pressure of gaseous phase
condense when…
vapor pressure of liquid phase is smaller than partial pressure of gaseous phase
boiling occurs when…
vapor pressure of liquid equals atmospheric pressure
melting occurs when….
vapor pressure of solid phase equals vapor pressure of liquid phase
above melting point - liquid vapor pressure is greater than solid
below melting point - liquid vapor pressure is less than solid
nonvolatile solute
solute with no vapor pressure
Raoult’s law (general)
vapor pressure of solution is proportional to the mole fraction of the liquid and vapor pressure of the pure liquid
P_v = X_a * P_a
for when nonvolatile solute added to liquid
P_v = X_a * P_a + X_b * P_b
volatile solute
solute with vapor pressure
Raoult’s law for nonvolatile solutes
if 97% of the solution is solvent, then the vapor pressure will be 97% of the vapor pressure of the pure solvent
Raoult’s law for volatile solutes
if 97% of the solution is solvent, then the vapor pressure will be 97% of the vapor pressure of the pure solvent plus 3% of the vapor pressure of the pure solute
vapor pressure of ideal solution is
sum of the individual partial vapor pressures
precipitation
reverse reaction of dissolving salt, slower rate than dissolution initially then equilibrate
saturated
rate of dissolution and precipitation are equal, concentration of dissolved salt has reached a maximum
solubility product K_sp
set equal to products over reactants raised to the power of their coefficients in the balanced equation, leave out pure solids and liquids
changes with temperature
crystallization is (exo/endothermic)
exothermic
solubility depends on
temperature and ions in solution
common ion added to a saturated solution…
will shift the equilibrium increasing precipitate, does not affect K_sp
common ion added to solution that is not saturated
will not shift the equilibrium (no equilibrium to shift)
spectator ions
no effect on equilibrium
pressure on a gas ___ solubility
increases
solubility of a gas is proportional to….
its vapor partial pressure
partial vapor pressure of a solution is always proportional to its ___
mole fraction
if component predominates as solvent,
Raoult’s law says the partial vapor pressure is proportional to the pure vapor pressure
if component represents tiny amount of solution,
vapor partial pressure is proportional to henry’s law constant
as temp increases, solubility of gas …
decreases