ch. 17 &19 test Flashcards
the common ion effect
whenever a weak electrolyte and a strong electrolyte containing a common ion are together in solution, the weak electrolyte ionizes less than if would if it were alone in solution.
buffers
solutions of a weak conjugate acid-base pair that resist drastic changes in pH
henderson-hasselback equation
pH=pKa+log([A-]/[HA])
addition of a strong acid or a strong base to a buffer is…
a neutralization reaction
titration of a strong acid w/ a strong base
S
titration of a strong base w/ a strong acid
backwards S
titration of a weak acid w/ a strong base
S shifts up
more soluble salt
has an anion that is the conjugate base of a weak acid.
unchanged solubility salt
has anion that is the conjugate base of a string acid
complex ion formation
metal ions can act as lewis acids and form complex ions with lewis base in the solvent
formation of what increases the solubility of certain salts?
complex ions
Amphoterism
amphoteric oxides and hydroxides are soluble in strong acids or base, because they can act either as acids or bases
metals with amphoterism behavior
Al^+3, Cr^+3, Zn^+3, and Sn^+2
Q=Ksp
the system is at equilibrium and the solution is saturated
Q<Ksp
more solid can dissolve, no precipitate forms
Q>Ksp
a precipitate will form
first law of thermodynamics
energy cannot be created or destroyed
enthalpy
is the heat absorbed or released by a system during a constant-pressure process
entropy
is a measure of the randomness in a system
spontaneous process
proceed without any outside assistance
experimental factors that affect spontaneous processes
temperature and pressure
reversible process
the system changes so that the system and surroundings can be returned to the original state by exactly reversing the process. this maximizes work done by a system on the surroundings
irreversible process
cannot be undone by exactly reversing the change to the system or cannot have the process exactly followed in reverse.
second law of thermodynamics
the entropy of the universe increases in any spontaneous process.
entropy equation
ΔS= Sfinal-Sinitial or ΔS=qrev/T(constant T)
reversible process
ΔS univ=ΔSsys +ΔSsurr=0
irreversible process
ΔS univ=ΔSsys +ΔSsurr>0
microstate
a single possible arrangement of position nd kinetic energy of molecules
Boltzman equation
S=klnW
entropy increases with
the number if microstates of a system
translational
movement of the entire molecule from one place to another
vibrational
periodic motion of atoms within a molecule
rotational
rotation of the molecule about an axis
the number of microstates possible for a system increase with
- an increase in volume
- an increase in temperature
- an increase in the number of atoms/molecules
entropy of a system increases for process where
- gases form from either solids or liquids
- liquids or solutions form from solids
- the number of gas molecules increases during a chemical reaction
factors that affect entropy
- physical state
- amount of substance more ->greater
- temp. higher->greater
- vol./pressure: higher vol. lower pressure -> greater
- size: larger -> greater
third law of thermodynamics
the entropy of a pure crystalline substance at absolute zero is 0.
entropy change equation
ΔS= ΣΔS^o(products)- ΣΔS^o(reactants)
ΔS^o
is the standrad moalr entropy and n and m coefficients of the balanced chemical equation
ΔS^o bullet points
- is not zero for the elements
- values of (g) > (l) > (s)
- increase with molar mass and number of atoms
ΔSsurr=
-ΔH/T
Gibbs free energy
enthalpy and entropy can be used to predict whether a reaction is spontaneous using the states function ΔG
ΔG=
ΔH-TΔS
ΔG>0
the forward reaction is spontaneous
ΔG=0
the system is at equilibrium
ΔG<0
the reaction is non spontaneous but spontaneous in the reverse direction
ΔG^o=
ΣΔGf^o(products)- ΣΔGf^o(reactants)
when -ΔH & +ΔS
spontaneous at all temperatures
when +ΔH & -ΔS
non spontaneous at all temperatures
when -ΔH & -ΔS
Spontaneous at low Temp; nonspontaneous at high temp
when +ΔH & +ΔS
spontaneous at high temp; nonspontaneous at low temp
