Chapters 14 & 15 Flashcards
Thirsty Solution
draws more water to itself
Solution
homogeneous mixture of 2+ substances or components
majority component in a solution
solvent
minority component in a solution
solute
nature has a tendency towards…
spontaneous mixing
substances tend to combine into what kind of mixtures
uniform
aqueous solution
water is the solvent and a solid, liquid, or gas is the solute
solubility
amount of a substance that dissolves in a given amount of solvent
most physical systems tend toward what kind of potential energy
lower
according to Coulomb’s law, potential energy BLANK as their separation BLANK
potential energy decreases as separation decreases
does the formation of a solution always lower potential energy of its constituent particles?
no
the tendency to mix is related to a concept called
entropy
entropy
measure of energy randomization or energy dispersal in a system
why do two ideal gases mix?
the tendency for energy to spread out wherever it is not restrained from doing so
miscible
two substances soluble in each other in all proportions
formation of solutions is drive by the tendency to do what
to mix, greater entropy
solutions form with what two kinds of relative interactions
1) when solven-solute interactions are greater than solvent-solvent interactions
2) solvent-solute interactions are close to equal to solvent-solvent interactions
what is the general rule of thumb for solubility?
like dissolves like
is forming a solution always a chemical reaction
no
if heat is evolved, the process is
exothermic
if heat is absorbed, the process is
endothermic
breaking of bonds is what kind of process
endothermic
forming bonds is what kind of process
exothermic
separating the solute into constituent particles is always what kind of process
endothermic
mixing, combining solvent particles is always what kind of process
exothermic
what is enthalpy of solution
sum of changes in enthalpy
what is heat of hydration
enthalpy change that occurs when 1 mol of gas solute ions is dissolved in water
heat of hydration is always largely what for ionic compounds
largely exothermic due to strong ion-dipole interactions
if the heat of solute is less than heat of hydration, what is the process
exothermic
if the energy requried to separate the solute into its constituent ions is greater than the energy given off when the ions are hydrated, what is the process
endothermic
what temperature are endothermic solutions to the touch
cool
what is reached when rates of dissolution and recrystallization have become equal
dynamic equillibrium
what is a saturated solution
dissolved solute is in dynamic equilibrium with the solid (undissolved) solute
what is a supersaturated solution
solutions containing more than the equilibrium amount of solute
what generally happens to supersaturated solutions after a time
excess solute normally precipitates out of solution
what effect does increasing temperature have on the solubility of solids
solubility increases
what is recrystallization
way to purify a solid
how does recrystallization work?
crystalline structure tends to reject impurities
what two things is the solubility of a gas in a liquid affected by?
temperature and pressure
describe the relationship between solubility of a gas with temperature and pressure
solubility of gas decrease with increasing temperature and increases with increasing pressure
what is Henry’s law
solubility (gas) = k (M/atm) x P (gas)
what is a dilute solution
solution that contains small quantities of solute relative to amount of solvent
concentrated solution
large quantities of solute relative to amount of solvent
molarity formula
moles solute/ volume solution
does molarity depend on temperature
yes
does molality depend on temperature
no
equation for molality
mols of solute/ kg of solvent
when is molality useful
comparing concentrations across different temps
what is ppm
parts per million, 10^6
what is ppb
parts per billion, 10^9
collagitive property
depends on number of particles dissolved in the solution
what are the 4 collagitive properties
vapor pressure lowering, freezing point depression, boiling point elevation, and osmotic pressure
nonvolatile
susbtance that doesn’t vaporize rapidly
in vapor pressure lowering, what component has a decrease in vapor pressure
solutions has a lower vapor pressure than the pure solvent
Raoult’s law
P(solution)= X(solvent) x Pure pressure(solvent)
what is the relatioship between vapor pressure and solvent
direct proportionality of vapor pressure to amount of solvent in the solution
What is another name for a volatile solute
nonelectrolyte
Raoult’s law for 2 component solution containing liquids A and B
1) Pa=Xa+P0a
2) Pb=Xb+P0b
3) Ptotal=Pa+Pb
what happens to a non-ideal solution in which solute-solvent interactions are stronger than solvent-solvent interactions
the solute tends to prevent solvent from vaporizing as readily
a nonvolatile solute does what to vapor pressure of a solution
lowers the vapor pressure, lifts the boiling point and lowers freeizing point
a highly concentrated solution will have what kind of freezing point, boiling point
low freezing point and high melting point
equation for change in Temp
Change in Temp=Km
osmosis
flow of solvent from solution of low solute concentration to one of higher concentration (from diluted to concentrated)
osmotic pressure
pressure required to stop the osmotic flow
osmotic pressure formula
pi=MRt
van’t Hoff factor
i = moles of particles in solution / moles of formula units dissolved
rate of a chemical reaction is a measure of
how fast the reaction occurs
the reaction portion of a reaction rate contains what kind of sign
negative
what happens to product concentrations as the reaction proceeds
the concentrations increase
what happens to reactant concentration in relation to time
as time increases, reactant concentration decreases
rate depends on BLANK of the reactants
concentration
in zero oder reaction, the rate is BLANK of concentration A
independent
in first order reaction, rate is BLANK to concentration of A
proportional
