Ch. 15 & 16 test Flashcards
chemical equilibrium
occurs when a reaction and its reverse reaction proceed at the same rate.
Kc
= (concentration of products) / (concentration of reactants)
Kp
= (pressure of products)/
(pressure of reactants )
the equilibrium constant depends on…
stoichiometry
Kp=
Kc(RT)^Δn
Δn
=(moles of gaseous product)-(moles of gaseous reactants)
If K»1
reaction favors products
If K«1
the reaction favors reactants
homogenous equilibria
occurs when all reactants and products are in the same place
heterogeneous equilibria
occur when a component in the equilibrium is in a different phase.
Q<K
nature will make the reaction proceed to products (right)
Q=K
reaction is in equilibrium
Q>K
nature will make the reaction proceed to reactants (left)
add more reactants
shift tor products
remove reactants
shift to reactants
add more product
shift to reactants
remove products
shift to products
Higher volume or lower pressure favors the side of the equation with
more moles
Lower volume or high pressure favors the side of the equation with
less moles
Endothermic
heat acts like a reactant; adding heat drives a reaction towards products. K increases
Exothermic
heat acts like a product; adding heat drives a reaction toward reactants. K decreases.
Catalyst
has no effect on the system at equilibrium it just helps you get their faster. Lowers activation energy.
inert substance non reactive
will not affect the equilibrium state
inert substance reactive
will shift
Arrhenius acid rule
is a substance that when dissolved in water increases the concentration of hydrogen ions (H+)
Arrhenius base rule
is a substance that, when dissolved in water, increases the concentration of hydroxide ions (OH-)
Bronsted-lowry acid
is a proton donor, must have at least one removable proton
Bronsted-lowry base
proton acceptor, must have at least one nonbonding pair of electrons
Lewis acid
electron pair acceptor
Lewis base
electron pair donor
conjugate acid-base pair
an acid and a base that differ by H+
the stronger the acid
the weaker the conjugate base
the weaker the acid
the stronger the conjugate base
the stronger the base
the weaker the conjugate acid
the weaker the acid
the stronger the conjugate base
water in the presence of acid
it acts like a base
water in the presence of base
it acts as an acid
equilibrium expression for auto-ionization is
Kc=[H3O+][OH-]
if an aqueous solution is neutral
[H+]=[OH-]
if an aqueous solution is acidic
[H+]>[OH-]
if an aqueous solution is basic
[H+]<[OH-]
strong acids
HCl, HBr, HI, HNO3, H2SO4, HCl3, and HClO4.
exist totally as ions in aqueous solutions
strong bases
soluble hydroxides, which are alkali metal and heavier alkaline earth metal hydroxides.
weak acids
only partially dissociate to ions
[H+]eq=[HA]init
strong acids
completely dissociate to ions
[H+]eq<[HA]init
Percent ionization=
(concentration of equilibrium)/
(Concentration of initial) x100
polyprotic acid
have more than one acidic proton
Kw=
KaxKb
cation can be
acidic or neutral
anion can be
acidic, basic, or neutral
Anions of strong acids
are neutral
Anions of weak acids
are conjugate bases
Protonated anions when Ka>Kb
acidic
Protonated anions when Ka<Kb
basic
if the salt contains an anion and cation that do not react with water
the pH is neutral
if the salt contains an anion that reacts with water and a cation that does not
the pH is basic
If the salt contains a cation that reacts with water and an anion that does not
the pH is acidic
if the salt contains both an anion and a cation that react with water
the larger K values determines pH
Factors that affect acid strength
Bond polarity
bond strength
stability of the conjugate acid
Binary acids
consist of H and one other element
oxyacids
consist of H,O, and one other element which is a nonmetal
as the oxidation number increases
the acidity increases
carboxylic acid
are organic acids containing the -COOH group
