chapter 6: equilibrium Flashcards
what is the equilibrium constant
K
K = [prod]/[react]
what does it mean if K >1, K<1
the reaction is product favored, reactant favored
do equilibrium constants have dimensions
no, they are dimensionless
in the equation aA+bB = cC+ dD what happens if A is a soute and when D is a gas
- A is a solute, [A] = 1/M
M = moles of solute /Liters - D is a gas, means that the pressure of D in bars/ 1 bar and written as Pd
what state is each quantitiy in the ratio given
at standard state
what are the different standard states
- conc. of solutes = mol/ L
- conc. of gases = bars
- do not include solids,liquids, and solvents because they are unity
what are some ways to manipulate the equilibrium constant
- reaction is reverse = 1/K
- two reactions are added together = multiply them together to get the new K
- if n reaction is added then K is the product of the n individual equilibrium constants
what is enthalpy
heat absorbed or released
what is entropy
the dispersal of energy into molecular motions, random
what is the enthalpy change
heat absorbed or released
what is the standard enthalpy change
heat absorbed when all reactants and products are in their standard states
if it is delta H is negative
exothermic
delta H is positive
endothermic
what is the symbol for entropy
delta S
what is the equation for entrop
S = qrev( heat abosrbed) / Temperature (kelvin)
what does a positive q mean what does a negative q mean
- heat is absorbed
- heat is removed
what states have higher entropy than the other
gas> liquid> solid
if S is positive, if S is negative
- greater entropy than reactants
- lower entropy than the reactants
which has more entropy, ions or solid salt
ions
what pushes a chemical reaction in the forward reaction
- H is (-)
- S is (+)
or both,
reaction is disfavored in the reverse reaction
what will decide whether the reaction will be favored if both H and S are positive
the gibbs free energy
What is the equation for gibbs free energy
G = change in H - T(change in S)
what sign is G if it is favored
negative
if G is negative what does it tell us about H and T
H has greater favorable influence than S because so it means that H is more negative
what is the equation for K using Gibbs
K = e^(change in G)/ RT
if K is greater than 1 what does it tell us about G
that G is negative because it is product favored reaction
what does a large K tell us
that something is very soluble in water
if K is greater than 1 is the reaction spontaneous
yes it is and it is not spontaneous when K is less than 1( because G is positive)
what is the Le chatelier’s principle
the direction in which the system proceeds to move back to equilibrium
- q<k
- q>k
3.q=k
- reactant favored
- product favored
- at equilibrium
what is the difference between thermodynamics and kinetics
- thermodynamics tells us the direction of the equation and kinetics tells us how fast it is going
what is the Ksp
equilibrium constant that gives us more information on how soluble a salt can be
what is a saturated solution
equilibrium with excess and undissolved solid
what happens if there is an aqeuous solution that is still left in contact with the excess solid
the solid will dissolve until the Ksp is satisfied
what is a mercurous ion Hg+
dimer that consists of two identical units bound together
what is disproportionation
the process in which an element in an intermediate oxidation state, gives products in both the higher and lower oxidation states
what reactions does solubility not account for
- hydrolysis
- disproportionation
- ion pairing
what is the common ion effect
salt is LESS soluble if one of its constituent ions is already present in the solution.
what does a small ksp indicate
that the reaction is less soluble
what is a complex ion
anion that precipitate metals are observed to form complex ions
what is a ligand
any atom or group of atoms attached to species of interest
what is an example of a ligand attached to a complex ion
- PbI+, PbI3 and PbI
- I is the ligand
- Pb is a lewis acid and I is a lewis Base
if anion X- precipitates metal M+, what is observed
high concentration of X- causes solid MX to redissolve
- increased solubility arises from the formation of complex ions like MX-2
