Chapter 16 Flashcards
Equilibrium
the state of a system by which the rate of the rxn in forward direction equals the rate of the rxn in reverse direction
What type of change is there during equilibrium
no net change
equilibrium constant expression is also called…
low mass action
what is the equilibrium constant expression
products over reactants
what two way can equilibrium be expressed
pressure or concentration
concentration units
M
pressure units
ATM
describe the relationship between Kc and Kp
Kc and Kp are proportional, but not necessarily the same
when you reverse a rxn, what must you do to the expression
reverse the equilibrium constant expression as well
ex: Kc= [B][C]/[A] ….. Kc’=[A]/[B][C]
equation for Kp to Kc
Kp=Kc(RT)^change in n
what is constant R
0.8206 L*atm/mol k
Homogeneous equilibrium, all reactants and products are…
in the same phase
In Keq expression, what species are included and what species are excluded
only gases and species dissolved in solution are included in the expression, EXLUDE any pure solids or pure liquids
does equilibrium constant depend on temperature?
yes
Kp has reactants and products expressed as..
pressure
what does the magnitude of the equilibrium constant represent
the extent of the reaction
Keq > 1…
reaction favors the products, shifts left
Keq < 1…
reaction favors the reactants, shifts right
Keq = 1
equilibrium
what is Q
reaction quotient, it is the measure of extent of reaction at given time… snapshot
Q < Keq
too many reactants, forms more products
Q > Keq
too many products, forms more reactants
if you add reactants what happens
rxn shifts right, more product formed
Q = Keq
at equilibrium, no net change
Le Chatelier’s Principle
a system at equilibrium which is disrupted to make it not at equilibrium will shift in a direction to re-establish equilibrium
what is the heat of rxn in exothermic rxn
change in Heat of rxn<0
when you add heat to exothermic rxn, what happens
rxn shifts left, Keq increases
when more reactant is made, what happens to Keq
Keq decreases
when you increase pressure, rxn will shift to what side
to side with less moles
what impact does a catalyst have on equilibrium
no change to equilibrium, catalyst only changes rate of rxn
equilibrium and rate of rxn are both affected by what?
temperature
Beer’s law equation
A=(epsilon)lc
what is special about epsilon (people don’t use it)
epsilon (molar absorbtivity constant) is generally unreliable because it depends on conditions
initial concentration is always..
before rxn, after dilution
Arrhenius definition
Acids: donate H+ ion in solution
Bases: donate OH- in solution
Lowry-Bronstead definition
Acids: proton donor
Bases: proton acceptor
Lewis definition
Acid: electron pair receptor
Base: electron pair donor
What ions in solution act as Lewis Acids?
metal ions
what is a ligand?
species that react with metal ions in solution, always anions or molecules with a lone pair
amphoteric:
species that can act as either acid or base
amphiprotic:
species that can accept/release Hydrogen ions
name the 6 strong acids
HCl, H2SO4, HBr, HI, HClO4, HNO4
what bases are strong bases
soluble metal hydroxides
what is an amine
organic compound derived from NH3
Acids form:
conjugate bases
how strong is the conjugate base of a strong acid
negligible base
Strong acids/bases form:
negligible conjugate bases/acids
weak acids and bases indicate what of the rxn’s direction
that the direction goes both ways
