Part 1 --Acid-Base Equilibria Flashcards
According to the Arrhenius Theory (1887), what is the definition of an acid and what is the definition of a base?
acid – A substance that liberates (releases) hydrogen ions
base – A substance that supplies (releases) hydroxyl ions
what is the name of the modern theory of acids and bases?
the Bronsted-Lowry theory
According to the Bronsted-Lowry theory, give the definition of an acid and a base
acid – a substance, CHARGED OR UNCHARGED, that is capable of donating a proton
base – a substance, CHARGED OR UNCHARGED, that is capable of accepting a proton from an acid
according to the modern theories of acids and bases, define “strong acid” and “weak acid”
give a specific example of each
strong acid – high tendencies to give up protons
ex: HCl in water
weak acid – low tendencies to give up protons
ex: acetic acid (CH3COOH) in water
the modern theory of defining strong acids and strong bases is _____ dependent
explain how acetic acid and hydrochloric acid could either be strong or weak acids given this statement
SOLVENT dependent
as mentioned, HCl is a strong acid in WATER. however, when placed in glacial acetic acid, it has WEAK acid properties. It has a low tendency to donate its proton
As mentioned, acetic acid is a weak acid in WATER. however, when placed in liquid ammonia, it has STRONG acid properties — high tendency to donate its protons
according to the modern theories of acids and bases, name and explain 2 classes of solvents
protophilic solvent (basic)
protogenic solvent
protophilic solvent — capable of accepting protons from the solute
protogenic solvent – a proton-donating compound (acids)
give 3 examples each of protophilic and protogenic solvents
protophilic solvents – acetone, ether, liquid ammonia
protogenic solvent – represented by ACIDS: acetic acid, sulfuric acid, hydrochloric acid
_____ solvents are also known as basic solvents
protophilic
what is a “protolytic reaction”?
reactions involving transfer of one or more protons
give an example of a protolytic reaction
give the full formula and identify the acid and base as well as conjugate pairs
HCl in water
HCl + H2O —> H3O+ + Cl-
acid = HCl
base = H2O
conjugate pair: HCl and Cl- & H2O and H3O+
notice: SINGLE HEADED ARROW. complete ionization.
HCl + H2O —> H3O+ + Cl-
this is complete ionization due to _______. There is no _____ in the final solution
this is complete ionization due to the SINGLE HEADED ARROW and the fact that HCl is a strong acid
there is NO HCl in the final solution. complete ionization occurred
there are ___ types of protolytic reactions.
name them
4 types:
ionization
neutralization
hydrolysis
displacement
according to the Lewis Electron Theory, define an acid and a base
acid – a molecule or ion that accepts an electron pair to form a covalent bond
base – the substance that provides the pair of unshared electrons by which the base coordinates with the acid
According to the Lewis Electron theory, the substance that PROVIDES the electron pair is the base or the acid?
base
define equilibrium
a balance between 2 opposing forces or actions
rate of forward reaction = rate of reverse reaction
differentiate between the pH conditions in the stomach and in the small intestine
stomach environment is much more acidic than small intestine environment
True or false
water is a base
false – water can act as an acid or a base depending on what it’s reacting with
give the formula for acetic acid in water and identify the acid and the base, as well as conjugate pairs
CH3COOH + H2O <—–> H3O+ + CH3COO-
acid = acetic acid
base = water
conjugate pairs:
CH3COOH and CH3COO-
H2O and H3O+
Give the formula for RATE of the FORWARD reaction of Acetic Acid in Water
Rf = k1 * [CH3COOH] * [H2O]
in general —-
rate of forward reaction is proportional to the concentration of the REACTANTS
Give the formula for the RATE of the REVERSE reaction of Acetic Acid in water
kr = k2 * [H3O+]^1 * [CH3COO-]^1
in general – rate of reverse reaction is proportional to the concentration of the PRODUCTS
^1 indicates 1 mole of that compound in reaction
at equilibrium, ___ = ____
Rf = Rr
aka……
k1 * [CH3COOH]^1 * [H2O]^1 = k2 * [CH3COO-] * [H3O+]
___ is the symbol for the dissociation constant of a weak acid
ka
k=…………………. (assume acetic acid in water)
k = [H3O+][CH3COO-]/[CH3COOH][H2O]
Ka =……
the dissociation constant of a weak acid
[H3O+][CH3COO-]/[CH3COOH]
why is water not in the formula for dissociation of a weak acid? (Ka)
water is in enough excess to be assumed as a constant
is HAc representing the ionized or unionized form of acetic acid?
unionized
ionized is Ac-
give 3 equations for dissociation constant of weak acid (Ka)
(assume acetic acid in water)
Ka = [CH3COO-][H3O+]/[CH3COOH]
Ka = x^2/(c-x)
ka= x^2/c
true or false
all salt forms can undergo complete ionization
false – most salt forms
name 2 formulas for dissociation concentration of a weak acid
x^2 = Kac
x = [H3O+] = square root of Kac
give formula for a non-ionized weak base in water
B + H2O <—–> OH- + BH+
give the dissociation constant for the ionization of weak bases in water
Kb = [OH-][BH+]/[B]
give the dissociation concentration formula for weak bases
[OH-] = square root of Kbc
give the formula for sodium acetate
Na+ CH3COO-
water can either be….
a weak acid or a weak base
when you increase the temperature, what happens to the rate of the reaction?
the rate of the FORWARD reaction is increased.
-higher dissociation
-favors product formation
why do we normally not mess with temperature too much to increase the rate of dissociation?
requires complicated storage for the product to remain at that temp
What are “monoprotic electrolytes”
acids that donate a single proton and bases that accept a single proton
what are “polyprotic electrolytes”
acids/bases that are capable of donating/accepting two or more protons
what is the term for an electrolyte that can accept/donate 2 protons? What about 3?
give examples
diprotic or dibasic
diprotic acid = carbonic acid
triprotic or tribasic
triprotic acid = phosphoric acid
give the formula for phosphoric acid
H3PO4
what is the term for a species that can function as either an acid or a base?
an AMPHOLYTE
what is neutral pH?
what is [H3O+] and [OH-] at this pH?
neutral pH is 7
both [H3O+] and [OH-] are 10^-7moles/L
pKw =
14 ALWAYS
pH + pOH = …….
pKw
pKa + pKb = …….
pKw
pK is a _____ exponent
dissociation
how to find the hydrogen ion concentration [H3O+] of a weak acid?
[H3O+] = square root of Kac
how to find the hydroxyl ion concentration [OH-] of a weak base?
[OH-] = square root kbc
what is the sulfuric acid formula
H2SO4
pKa = ……
-log Ka
what is Ka?
dissociation constant
