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Gravity
Terms in this set (38)
Poorly Soluble Salt at equilibrium
reversible
rate of dissolving equals the rate of reforming= equilibrium
reaction quotient means ion product
ion product is the equilibrum constant
Ksp
equilibrium constant of a poorly soluble salt
Factors that change solubility (3)
Temperature
solvent
other solutes
Solubility
the maximum amount of salt that can be dissolved in a given amount of solvent at a given temperature
Solubility and Ksp relationship
higher Ksp, higher solubility, the smaller the exponent
calculate the ksp using solubility
use the salts solubility
use reaction quotient formula Qp=[products]/[reactants]
make sure to use the stoichiometry
calculate solubility using Ksp
let one be x, at equilibrium ion product will equal Ksp
ksp= [products]/[reactants]
solve for x
Addition of common ion on soluability
if you add a highly soluble salt to a poorly soluble salt at equilibrium, it will decrease the solubility of a poorly soluble salt (highly soluble salt will take over)
predict solubility of PSS with a common ion
use reactant quotient expression
fill in the known concentration of the common ion, solve for x for the non common ion, this is the solubility constant of the PSS
iteration method
use if we cannot use simplifying assumptions
plug in known value and solve for x as normal
keep going using the previous ksp value
go until two iterations are close to eachother
Addition of an acid on solublility
addition of a strong acid, negative ion of salt accepts proton making parent weak acid, shifts equilibrium to the right causing more salt to dissolve
addition of weak base/ metal hydroxide
addition of base increases the hydroxide concentration
working like the common ion effect and shifts the reaction to the right
ph and solubility
as ph increases solubility decreases
as ph decreases, solubility increases but it makes a different salt than you started with
complex ion
metals that dissolve in water become surrounded, forming a complex, ALWAYS IN SOLUTION, can be other molecules than water
complex on solubility
a formation of a complex takes the ion out of the equation and causes the equation to shift toward the right
thermodynamics
energy changes in chemical reactions, entropy and enthalpy
1st law of thermodynamics
conservation of energy
2nd law of thermodynamics
a process that is spontaneous in 1 direction cannot be spontaneous in another without an increase in entropy
entropy
a measure of disorder in a system
can be chemical compounds or reactions
disorder is the movement of atoms/molecules/bonds
degrees of freedom- how molecules vibrate rotate and stretch
Boltzman equation
S=klnW
s=disorder
k= proportionality constant
W= degrees of freedom
Ways a system can be disordered (6)
1) gas>liquid>solid
2) more molecules of gas increase the disorder
3)the higher the temperature the higher the disorder
4)more complex molecules, more disorder
5) more space, more disorder
6)more different types of atoms, more disorder
delta S
change in entropy/disorder, absolute values because a perfect crystalline solid is zero
G0, S0, H0 (prime)
measurements taken at standard values, 25 degrees, 1 molar solution
state function
value depends on state at the specific moment
change in S, H or G
products times moles - reactants times moles
Exothermic reaction and Entropy
if heat is transferred from system to surroundings, temp surroundings increase and entropy increases
Endothermic reaction and Entropy
if heat is transferred from surroundings to a system, temp of surroundings will decrease, decreasing entropy
How to tell if spontaneous
delta H would be negative and exothermic because it releases gas and heat
delta s would be positive because disorder will increase
delta g would be negative as well
Gibbs free energy equation
G=H-TS or deltaG=deltaH-T(deltaS)
delta G is negative for spontaneous
if delta S is positive, delta G is more neg as temp rises
if delta S is negative, delta G is more positive as temp rises
Delta H is positive, Delta S is negative
delta G is positive, nonspontaneous in ALL TEMPS
Delta H is negative, Delta S is positive
Delta G is negative, Spontaneous in ALL TEMPS
Delta H is negative, Delta S is negative
Delta g is negative at low temperatures, positive at high temperatures
spontaneous at low temps, nonspontaneous at high temperatures
Delta H is positive, Delta s is positive
delta g is negative at high temperatures and positive at low temperatures
spontaneous at high temperatures, nonspontaneous at low temps
Calculate switching point from spontaneous to nonspontaneous
use delta g= deltah-(t)(delta s) where delta g is zero
Effect of reactants and product concentrations on free energy
invoke the reaction quotient
delta g= delta g prime+ RTlnQ
if products increase/reactants decrease, Q increases and delta g becomes more positive b/c itll go backwards
if products decrease/reactants increase, Q decreases and delta G becomes more negative b/c itll go forwards
Free energy and equilibrium constant
at equil,, Q=K and deltaG=0
Keq=e-deltaGprime/RT
Kinetically Stable Rxn
exothermic
reactant energy is higher than product energy
deltaG is negative
spontaneous overall b/c negative
Thermodynamically stable rxn
endothermic
reactant energy is lower than products
nonspontaneous because delta G is positive
couple with a spontaneous rxn to 'make' proceed
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