Equilibrium (AS/A level) Flashcards
four charactertistics of equilibrium
dynamic
forward = backward reaction at same rate
concentration of r/p remain constant
closed system
what is la chateliar’s principle
If one or more factors that affect an equilibrium is changed, the position of equilibrium shifts in the direction that reduces the change
decreasing concentration of reactants causes
equilibrium to move left
whichever side you take stuff off, equilibrium shifts to the side to restore ok
ok
increasing pressure causes
equilibrium moves to less molecules side
how does temperature affect equilibrium
depending on exo/endo
both forward/backward rate increases
which factor is Kc dependant
temperature
how does catalyst affect equilibrium
no effect
no effect on delta H
remember to practice mole ratios
ok
what is homogeneous equilibrium
everything present in the same phase
what is heterogeneous equilibrium
things present in more than one phase
definition of an acid
proton donor
definition of a base
proton acceptor
what are conjugate pairs
HCl (acid) = cl- (conjugate base)
differ by one proton
definition of ionic product of water
[H+][OH-]mol2dm-6 (Kw)
1 x 10^-14
definition of pH
-log[H+]
how to find pH of strong acids
[H+] = concentration of acid
how to find pH of strong bases
using Kw
[OH-] = concentration of base
how to find pH of weak acids
Ka = [H+]^2/[HA}
what does high value of Ka mean
equilibrium toward right = stronger acid
pKa formula
-log[Ka] (less positive = more acidic)
definition of indicator
Acid-base indicator is a dye/mixture that changes colour over a specific pH range. The weak acid and conjugate base has different colours. Hln ⇌ H+ + ln-
what does pKa show
transition of colour
where is equivalence point
midpoint of fall
