GenChem10 (Acids and Bases) Flashcards
An indicator which turns red in acidic solution and blue in basic solution
Litmus Paper
Defines acids as a species that produces H+ (a proton) in an aqueous solution and a base as a species that produces OH- (a hydroxide ion) in an aqueous solution.
Arrhenius Definition
Defines acids as a species that donates protons, and a base as a species that accepts protons.
Bronsted-Lowry Definition
Defines an acid as an electron pair acceptor and a base as an electron pair donor.
What are the exceptions?
Lewis Definition
BCl3 and AlCl3
Acids formed from anions whose names end in ide have the prefix _____ and the ending ___
hydro, ic
hydrofluoric acid - HF
hyrdobromic acid -HBr
Acids formed from oxyanions are called
If the oxyanion ends in -ite, it has more/less oxygen and the acid ends in ______
If an oxyanion ends in -ate, it has more/less oxygen and the acid ends in
oxyacids
An oxyanion ending in -ite has less oxygen and the acid ends in -ous.
An oxyanion ending in -ate has more oxygen and the acid ends in -ic
ClO- ClO2- ClO3- ClO4- NO2- NO3-
ClO-Hypocholorite ClO2- Chlorite ClO3-Chlorate ClO4-Perchlorate NO2-Nitrite NO3-Nitrate
HClO HClO2 HClO3 HClO4 HNO2 HNO3
Hypochlorous acid Chlorous Acid Chloric Acid Perchloric Acid Nitrous Acid Nitric Acid
If Ka= 1.8*10^-5, what is pka?
slightly less than 5
exactly 4.74
What property do strong acids and bases have?
They completely dissociate into there component ions in aqueous solution
Name the strong acids that you should be aware of
HCl HBr HI HNO3 HClO3 HClO4 H2SO4
What is an amphoteric (amphoprotic) compound?
It can be an acid or base
ex) HCO3-
The stronger an acid the weaker/stronger the base
Weaker the base!
Name the strong bases that you should be aware of.
Group I and II metal hydroxides
LiOH NaOH KOH RbOH CsOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
Magnesium not included because it’s not soluble
What is the equation for Ka?
Ka=[H30+][A-]/([HA])
What is the equation for Kb?
Kb=[B+][OH-]/[BOH]
A reaction with acids and bases reacting with each other, forming a salt and often water
Neutralization Reaction
Ex: HA + BOH —> BA + H2O
A reaction in which salt ions react with water to give back an acid or base, also considered the reverse of a neutralization reaction
Hydrolysis
What are the 4 combinations of strong and weak acids/bases?
SA/SB
SA/WB
WA/SB
WA/WB
What are the products of a reaction between equal concentrations of a SA and SB?
What is the resulting pH?
Do the resulting ions react with water?
Salt and water
pH=7 (neutral)
No
What is the product of a reaction between a strong acid and a weak base?
Salt, usually no water
What happens when HCl reacts with NH3 in aqueous solution?
Why does this occur?
NH3 + HCL —> NH4(+) + CL(-)
NH4(+) + H2O —-> NH3 + H3O(+)
The conjugate acid (NH4+) is stronger than the conjugate base (CL-) of the strong acid HCL. NH4 reacts with OH, producing an excess of H+.
What is the product of a reaction between an weak acid and a strong base?
A basic solution
What is the product of a reaction between a weak acid and a weak base?
It depends upon the Ka and Kb for the reactants, whichever is higher will cause the solution to be acidic or basic
What is the one diprotic strong acid?
How many acid equivalents does it produce?
H2SO4
2
What is the normality of a concentration of 2M H3PO4?
6N
What is the equivalent weight of H2SO4 (molecular weight = 98g/mol)
49 g; that is, 49 g of H2SO4 releases 1 acid equivalent
A species that can act as an acid or a base, depending upon its chemical environment, is called
amphoteric or amphiprotic
Ex) Water
When water reacts as a base, it behaves as an
When water react with an acid, it behaves as a
Acid
H2O + B- —–> NH + OH-
Base
H2O + HA —-> H3O(+) + A-
The conjugate base of a polyprotic acid is usually
amphoteric
ex) HSO4
The hydroxides of certain metals (Al, Zn, Pb, Cr) are
Amphoteric
A procedure used to determine the molarity of an acid or base. It is accomplished by reacting a known volume of a solution of an unknown concentration with a known volume of a solution of a known concentration
Titration
In titration, the point at which the acid equivalents equal the base equivalents is known as the
Does this point always occur at pH of 7?
Equivalence point
No, only for strong acids/strong base titrations
Under what conditions are there several equivalence points?
When titrating polyprotic acids or bases
Weak organic acids or bases that have different colors in their undissociated and dissociated states. Used in titrations, are in low concentration and don’t alter the equivalence point
Indicator
The point at which the indicator changes color is called the
This is not the equivalence point, can the volume of the endpoint be used?
End point
Because there is very little difference in volume between the equivalence point and the end point (look at the graph on p. 397), and it may be corrected for or ignored.
What is the equation to calculate the volume added in a titration using normality?
What is the equation for normality?
What about gram equivalents?
VaNa=VbNb
gram equivalents/volume of solution
gram equivalents
How is the titration curve of a weak acid using a strong base different from a strong acid using a strong base?
The pH is higher at the beginning and the pH changes most significantly early on.
Importantly, the equivalence point is in the basic range.
Consists of a mixture of a weak acid and its salt, or a mixture of a weak base and its salt.
Buffer Solution
ex: acetic acid (CH3COOH) and its salt (CH3COO-Na+)
ammonia (NH3) and its salt ammonium chloride (NH4+ CL-)
What is the equation used to estimate the pH of a solution in the buffer region where the concentrations of the species and its conjugate are present in approximately equal concentrations
For a weak acid buffer solution:
For a weak base buffer solution:
pH=pKa + log[conjugate base]/[weak acid]
pH=pKb + log[conjugate acid]/[weak base]
