rate of reaction is
directly proportional
to the concentration
of substance
Rate=k[X]
2nd order
Rate of reaction is directly
proportional to the square
of the concentration of the
substance
Rate=k[X]^2
0th order
Rate of reaction is not proportional to
the concentration of the substance, but
the substance is still necessary for the
reaction to take place
Rate=k[X]^0
Rate
determining
step
The slowest step in
the reaction is what
is considered the
rate determining
step.
the other steps are so fast comparatively, that
to concentrations of the reactants have no
overall effect on the rate of reaction
Kc
General Formula: aA + bB <--> cC
dD Kc= ([C]^(c)[D]^(d) / [A]^(a)[B]^(b)
Kc is the equilibrium constant
the Kc for a reaction is
constant if temperature
is constant
Changing
concentrations of
reactants/products
in equilibrium will
have no effect on
the value of Kc
is the concentration of one of
the substances is changed,
then the position of
equlibirum will shift to
produce more on the other
side of equation, until a new
dynamic equilibrium forms
with the same Kc
Pressure also has no
effect on Kc, for the
same reasons that
concentration doesn't
When Kc is greater than one. Then
the position of equilibrium, moves to
the RHS. When it is below one, it
moves to the LHS
Kc value changes with
temperature, because temperature
causes the concentrations of the
reactants/products to change
Acids and bases
in
bronsted-lowry
theory, bases
are proton
acceptors, and
acids are proton
donors
When an acid
dissolves into water,
it disassociates into
positive hydrogen ion
and a negative ion.
HA<--->H+ + A-
strong acids fully
disassociate into ions
Ph is a measure of
the concentration of
H+ ions in solution.
Ph= - Log10[H+]
Ka is the disassociation
constant for acids. Kc=
[H][A]/[HA]
For every acid,
there is a value
of Ka which is
constant
the higher the Ka
value, the stinger the
acid (a perfect strong
acid would have an
infinite Ka value)
there is also the extra
value of pKa, which has
the same relationship as
with pH. The higher the
value of pKa, the weaker
the acid
Kw is the water dissociation
constant. it is always 10^(-14)
Kw=[OH][H]
pKw=pH +pOH
pKw=14
Buffer solutions
A buffer solution is a mixture
of a weak acid and its
conjugate base (which usually
comes from a salt). this
resists a change in pH when
small amount of acid/alkail
are added
when a acid is added, it increases [H+]
which reacts with A-, and shift equilibrium
to the left. When an alkali is added, it
reacts with the few H+ ions to produce
water. This reduces the concentration of
H+ causing the equilibrium to shift to the
right, to restore the lost H+ ions
The Ph of buffer solutions can
be worked out. But be aware
that H+ does no longer equal A-