Unit 2: Acids and Bases Flashcards
1
Q
Arrhenius Definition: Acids are compounds which break apart (ionize or dissociate) to give off an ________ ion (which combines with water to form the __________________-)
A
H+
hydronium ion, H3O+
2
Q
Arrhenius Definition: Bases are compounds that break apart (ionize or dissociate) to give off a __________________-
A
hydroxide ion, OH-
3
Q
Note that you will sometimes see the HCl equation written this way:
HCl (aq) → H+ (aq) + Cl– (aq)
what really exists?
A
what really exists is H3O+, not H+. If you see an equation like this shortcut, just know that really you should add a water molecule to the left and H+ should be H3O+ on the right.
4
Q
Bronsted-Lowrey Definition: Acids are proton ____________.
A
donors
5
Q
Bronsted-Lowrey Definition: Bases are proton ___________.
A
acceptors
6
Q
Lewis Definition: Acids are electron pair ___________.
A
acceptors
7
Q
Lewis Definition: Bases are electron pair ___________.
A
donors
8
Q
A strong acid ionizes _____________ in water to create hydronium ion.
A
completely
9
Q
A weak acid ionizes ______________ in water to create hydronium ion.
A
only partially
10
Q
Notice how we used a one-way arrow for the ________________, indicating we expect that reaction to go essentially to ____________, but we used equilibrium arrows for the _______________, indicating that we expect the equilibrium mixture to be ______________________.
A
strong acid, completion
weak acid, a mix of reactants and products.
11
Q
strong bases
A
LiOH
NaOH
KOH
RbOH
CsOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
12
Q
strong acids
A
HCl
HBr
HI
HClO4
HClO3
H2SO4
HNO3
13
Q
Binary Acid:
A
Contains H plus one other element
Example: HCl (aq)
14
Q
Organic (carboxylic) Acid:
A
Contain carboxyl group (-COOH)
Example: acetic acid, CH3COOH (aq)
Note that for this molecule, only the H that is part of the -COOH group is considered acidic. That is, only that proton is likely to be donated. The C-H bonds are expected to stay intact. Hence, this molecule would have one acidic hydrogen.
15
Q
Ternary Acid (Oxoacid):
A
Contains three elements, with H attached to oxygen atom(s)
Examples: Nitrous, HNO2 (aq); nitric, HNO3 (aq)
16
Q
Naming Binary Acids
A
HX, “hydro(X)ic acid”
Examples: HCl is hydrochloric acid; HF is hydrofluoric acid
17
Q
Naming Ternary Acids: Polyatomic ions ending with “-ate” shift to “_______ acid”
A
-ic
Example: HNO3 is nitric acid.
18
Q
Naming Ternary Acids: Polyatomic ions ending with “-ite” shift to “_________ acid”
A
-ous
Example: HNO2 is nitrous acid.
19
Q
Monoprotic acids have _________________.
A
one acidic proton
Examples: HCl, HNO3
20
Q
Polyprotic acids have _____________________.
A
more than one acidic proton
21
Q
Diprotic:
A
has two acidic protons.
Example: sulfuric acid, H2SO4
22
Q
Triprotic:
A
has three acidic protons
Example: phosphoric acid, H3PO4
23
Q
H3PO4 would be classified as a ______________ and would be named _________________.
A
ternary acid, phosphoric acid
24
Q
HBr is a _________________ acid and would be named _________________
A
binary, hydrobromic acid
25
It turns out that water is ______________, meaning it can accept or donate a proton. It can behave as an acid or a base.
amphiprotic
26
ACIDIC solution concentration:
[H+] > [OH-]
27
NEUTRAL solution concentration:
[H+] = [OH-]
28
BASIC solution concentration:
[H+] < [OH-]
29
the general form of "neutralization reactions":
Acid + Base → Salt + Water
30
The point at which we have perfect stoichiometric ratios of the acid and base (the point where we have used up all of the acid and all of the base, with no excess of either) is called the ______________ point
equivalence
31
An ________________ is a substance that changes color based on the pH of the solution.
acid/base indicator
(not the cause of the changes of the pH)
32
The equivalence point is the point when _____________________. The end point is the point when __________________.
stoichiometric amounts of acid and base have reacted, the indicator changes color
33
For an acid base indicator to work well for your titration, it should change color
at a pH near the equivalence point pH
34
When we have an acid reacting with water, we give the equilibrium constant a special symbol:
Ka
35
When you dissolve 1 mole of HBr in enough water to make 1 L solution, you expect the resulting solution to have ___________. When you dissolve 1 mole of HNO2 in enough water to make 1 L solution, you expect the resulting solution to have _____________.
[H+] = 1 M, [H+] <1 M
36
Now think about the reverse reaction. If the reaction was moving in reverse, H3O+ goes to H2O, meaning it is donating a proton and hence acting as an __________. F- goes to HF, accepting a proton and hence acting as an __________.
H2O (l) + HF (aq) ⇌ H3O+ (aq) + F– (aq)
acid, base
H2O (l) + HF (aq) ⇌ H3O+ (aq) + F– (aq)
Base Acid Acid Base
37
A conjugate acid-base pair always consists of two molecules (or ions) that differ...
by one proton
38
An acidic salt is a salt that, when dissolved in water, produces a solution with a pH_______. It does this because there is a weak acid "hidden" in the salt formula.
pH<7
39
A basic salt is a salt that, when dissolved in water, produces a solution with a pH_________. It does this because there is a weak base "hidden" in the salt formula.
pH>7.
40
You dissolve a salt in water and measure the pH of the resulting solution. If the pH is 3.4, you know that the salt was a(n)
acidic salt
41
R: The top line is the _________ itself.
I: The next line is the ________ concentration, moles, or pressure.
C: The third line is the ___________, the amount that reacts or forms in order to reach equilibrium.
E: The final line is the actual ___________ amounts for each species.
Reaction, Initial, Change, Equilibrium
42
A higher Ka means that equilibrium lies more towards the ____________.
products
43
The protonated version will be the ________ and the deprotonated version will be the _________.
acid, base
44
While most weak acids and bases ionize very little, that small amount of ionization can still have a big effect on the _________ of the solution.
pH
45
Our expectation of the neutralization reaction going to completion is true whether our acids and bases...
are strong or weak
46
Classify NaCl as a neutral, acidic, or basic salt.
neutral
The parent acids and bases of NaCl (HCl and NaOH) are both strong.
47
Classify KCH3COO as a neutral, acidic, or basic salt.
basic
The acetate ion will act as a weak base.
48
Classify NH4Cl as a neutral, acidic, or basic salt.
acidic
The ammonium ion (NH4+) is the conjugate acid of ammonia (NH3).
49
hydronium ion
H3O+
50
hydroxide ion
OH-
51
LiOH
Lithium hydroxide
52
Lithium hydroxide
LiOH
53
LiOH is not as ____________ as the other strong bases
soluble
54
CsOH
Caesium hydroxide
55
Caesium hydroxide
CsOH
56
CsOH
Caesium hydroxide
57
Calcium hydroxide
Ca(OH)2
58
Ca(OH)2
Calcium hydroxide
59
Sr(OH)2
Strontium hydroxide
60
Strontium hydroxide
Sr(OH)2
61
Ba(OH)2
Barium hydroxide
62
Barium hydroxide
Ba(OH)2
63
Sodium hydroxide
NaOH
64
NaOH
Sodium hydroxide
65
Potassium hydroxide
KOH
66
KOH
Potassium hydroxide
67
Rubidium hydroxide
RbOH
68
RbOH
Rubidium hydroxide
69
common ion effect
since the extent of the reaction is determined by the various concentration of the molecules and ions in solution, the reaction will be affected when occurring in a solution that already has some of those molecules or ions present from another source. In our example, more HF ionizes in pure water than when in a solution that already contained F– ions.
70
Buffer solutions protect from large changes in ________ because they contain both an acid and a base. It turns out it can’t be just any acid or base, though; it has to be a _________________, both in the same solution.
pH, conjugate acid-base pair
71
Ratio: A ________ acid:conjugate base mix is best for a buffer, but a solution with up to a _______ or _______ ratio can work as a buffer solution.
1:1
10:1
1:10
72
HCl
Hydrochloric acid
73
Hydrochloric acid
HCl
74
HBr
hydrobromic acid
75
hydrobromic acid
HBr
76
HI
hydroiodic acid
77
hydroiodic acid
HI
78
HClO4
perchloric acid
79
perchloric acid
HClO4
80
HClO3
chloric acid
81
chloric acid
HClO3
82
H2SO4
sulfuric acid
83
sulfuric acid
H2SO4
84
HNO3
nitric acid
85
nitric acid
HNO3
86
What is the deprotonated form of nitrous acid?
NO2–
87
The Henderson-Hasselbalch formula allows us to determine if the majority of a compound will be in the protonated or deprotonated form at a given pH by comparing the pH of the solution to the _____. The exact _____ of protonated form and deprotonated form can be obtained from the Henderson-Hasselbalch equation.
pKa ; ratio
88
The buffer capacity of a buffer solution is the total amount of acid or base that can be added to the buffer before ____________ all of __________ of the forms of the compound.
neutralizing, one
89
A buffer is composed of NH3 and NH4Cl. How would this buffer solution control the pH of a solution when a small amount of a strong base is added?
The OH– reacts with the NH4+.
The conjugate acid component (NH4+) of the buffer would react with the added base (OH–).
90
Thymolphthalein has a pKa of about 10.0. The protonated version (HA) of the molecule is clear and the deprotonated (A-) version is blue. If you put thymolphtalein in a solution that has a pH of 6.2, you would expect to have more of the ____________ molecule and you would expect the solution to appear _________
protonated, clear
91
Bromocresol green has a pKa of about 4.6. The protonated version of the molecule is yellow and the deprotonated version is blue. If you put bromocresol green in a solution that has a pH of 6.2, you would expect to have more of the _____________ molecule and you would expect the solution to appear ____________
deprotonated, blue
92
A base must contain a hydroxide group.
False
93
HCN is classified as a weak acid in water. This means that it produces...
a relatively small fraction of the maximum number of possible hydronium ions.
94
What is the conjugate acid of NO3—?
HNO3
95
The conjugate base of H2SO4 is:
HSO4–
96
A water solution of sodium acetate is basic because...
the acetate ion acts as a Bronsted-Lowry base in a reaction with water.
In water, sodium acetate dissociates into sodium ions (spectator ions) and acetate ions which hydrolyze to produce hydroxide ions.
CH3COO– + H2O ⇌ CH3COOH + OH–
The acetate ion accepts a proton from a water molecule, and is thus a Bronsted-Lowry base.
97
Ka is the equilibrium constant that describes...
an acid reacting with water to make hydronium ion and conjugate base.
98
__________ acids dissociate 100%. Therefore, _________ acids cannot exist in solution along with their ________________ and, by definition, cannot form ____________________.
Strong, strong, conjugate bases, buffer solutions
99
Neutralizing a weak acid with a strong base will create a ______________ and water.
basic salt
100
pKa + pKb for an acid/conjugate base pair will add up to ________.
14
101
If you place a molecule in a solution where the pH is less than the pKa, the molecule will be mostly
protonated
102
If the pH is greater than the pKa, the molecule will be mostly
deprotonated
103
If the pH equals the pKa, the molecule is equal parts...
protonated and deprotonated
104
The reason why CO2 lowers the pH when it is dissolved in water is that CO2 reacts with water to form _____________. __________ can then give up a proton, increasing the _____ concentration of the water and lowering the pH
carbonic acid, H2CO3, carbonic acid, H+
105
Is H2O(ℓ) acting as an acid or a base?
H2O(ℓ) + NH4+(aq) → H3O+(aq) + NH3(aq)
base, accepts a proton becoming H3O+
106
Is H2O(ℓ) acting as an acid or a base?
CH3−(aq) + H2O(ℓ) → CH4(aq) + OH−(aq)
acid, donates a proton making OH-
107
balanced chemical equation for calcium hydroxide dissolved in water:
Ca(OH)2 (aq) --> Ca2+ (aq) + 2OH- (aq)
108
write product for reaction:
H2O (l) + LiOH(aq) -->
Li+ + H2O + OH-
109
Doubling the concentration of the acid ________ the pH by _______ pH units no matter what the initial and final concentrations are
lowers, 0.3
110
Raising the concentration of the acid by a factor of 10....
lowers the pH by one pH unit
111
Decreasing the acid concentration by a factor of 10...
raises the pH by one pH unit
112
Doubling the concentration of the base ________ the pH by ______ pH units
raises, 0.3
113
Decreasing the concentration of the base by a factor of 10...
lowers the pH by 1 pH unit
114
Increasing the concentration of the base by a factor of 10...
increases the pH by 1 pH unit
115
pH formula
pH = -log [H+]
116
pOH formula
pOH = -log [OH-]
117
pH and pOH relationship
pH + pOH = 14
118
[H+] formula
[H+] = 10^-pH
119
[OH-] formula
[OH-] = 10^-pOH
120
The pH scale is a ________ scale that expresses the ___________ ion concentration, [H3O+],
log, hydronium
121
pH of solution that is 1.0 x 10^-10 M in HCl
~7, concentration of acid is extremely small compared to hydronium ion concentration in water, thus pH will be close to that of pure water
122
molarity of a solution with barium hydroxide with a pH = 12.00?
0.005M
remember that it has 2 moles of OH-
123
for solids, moles of acid or base =
grams/molar mass
124
for solutions, moles of acid or base =
Molarity x Volume
125
a problem using words like neutralize, neutralization, titrate, titration, equivalence point, or end point uses what equation?
(moles of acid) (# of H+ in the acid) = (moles of base) (# of OH- in the base)
126
Three ways to make a 1:1 buffer:
1) Mix equal moles of weak acid and conjugate base, or weak base with conjugate acid.
2) Add strong base to a weak acid until half of the moles of the acid are converted to the conjugate base form.
3) Add strong acid to a weak base until half of the moles of base are converted to the conjugate acid form.
127
[A-] =
base
128
[HA-] =
acid
129
a =
b =
c =
1
Ka
-KaCacid
130
the stronger the weak acid...
the weaker the conjugate weak base
131
strong acids do not have
conjugate bases
132
NH4Cl is just
NH4+
133
Just a weak acid and nothing else:
[H+] = √KaCacid
134
Just a weak base and nothing else:
[OH-] = √KbCbase
135
quadratic formula
[H+] = (-Ka +- √Ka^2 - 4(KaCacid))/2
*use when Ka is bigger than 10^-3
136
when to use double arrows?
when it is JUST a WEAK base or acid with water
137
what is the dominant species in solution at equivalence point of a weak base-strong acid titration?
weak acid
138
SA + SB will have a pH of ____ at equivalence point because it produces _______ salt water
7, neutral
139
The higher the Ka, the more the acid ______________.
dissociates
