Acids and bases Flashcards
1
Q
Define acids (Arrhenius’ theory)
A
An acid produces H⁺ ions in water.
2
Q
Example of an acid HCl ⇾
A
H⁺ + Cl-
3
Q
What did Arrhenius’ theory allow?
A
The existence of independent H⁺ ions.
4
Q
Arrhenius’ theory allowed the existence of independent H⁺ ions. Has this theory been proven true or false?
A
False
5
Q
What does the H⁺ ion react with and what is formed?
A
- React with water
- Forms H₃O⁺
6
Q
What is H₃O⁺ known as?
A
Oxonium ion / hydronium ion
7
Q
Were non-polar organic solvents included in Arrhenius’ theory?
A
No
8
Q
Define base (Arrhenius’ theory)
A
A base produces OH- ions in water.
9
Q
What is an alkali?
A
A base that is soluble in water.
10
Q
Example of a base NaOH ⇾
A
Na⁺ + OH-
11
Q
Example of a base Mg(OH)₂ ⇾
A
Mg₂⁺ + 2OH-
12
Q
Is NaOH an alkali?
A
Yes
13
Q
Is Mg(OH)₂ an alkali?
A
No
14
Q
State a problem with Arrhenius’ theory.
A
Arrhenius’ theory of bases excluded common bases such as NH₃.
15
Q
Give the general equation for acids dissociating in solution (where HA is an acid).
A
HA + H₂O ⇾ A- + H₃O⁺
16
Q
Define monobasic acids.
A
A monobasic acid produces one H⁺ ion in solution. e.g. HCl and HNO₃.
17
Q
Define dibasic acids
A
A dibasic acid produces two H⁺ ions in solution e.g. H₂SO₄.
18
Q
Define tribasic acids
A
A tribasic acid produces three H⁺ ions in solution e.g. H₃PO₄.
19
Q
Who put forward a newer definition?
A
Bronsted-Lowry
20
Q
Define acid (Bronsted-Lowry theory)
A
An acid is a proton (H⁺) donor.
21
Q
Define base (Bronsted-Lowry theory)
A
A base is a proton (H⁺) acceptor.
22
Q
What is the acid and base in : HCl + H₂O ⇾ Cl- + H₃O⁺
A
Base - H₂O
Acid - HCl
23
Q
What is the acid and base in : NH₃ + H₂O ⇾ NH₄⁺ + OH-
A
Base - NH₃
Acid - H₂O
24
Q
What is water as it can act as both an acid and a base?
A
Amphoteric
25
Define amphoteric
A substance that can act as both an acid and a base.
26
What is the acid and what is the base : H₂O + H₂O ⇾ H₃O⁺ + OH-
1st H₂O - Acid
| 2nd H₂O - Base
27
An acid only acts as an acid in the …………...
Presence of a base.
28
Define conjugate pairs
Two substances that differ by one proton.
29
Define conjugate acid
A base plus a H⁺ ion.
30
Define conjugate base
An acid minus a H⁺ ion.
31
Give three examples of conjugate pairs with HCl, HNO₃ and NH₃.
HCl / Cl-
HNO₃ / NO₃-
NH₃ / NH₄⁺
32
Why is HCl / Cl- a conjugate pair?
As they differ by only one proton.
33
Pick out the acid, base, conjugate acid and conjugate base form the following equation : H₂SO₄ + H₂O ⇾ H₃O⁺ + HSO₄-
Acid - H₂SO₄
Base - H₂O
Conjugate acid - H₃O⁺
Conjugate base - HSO₄-
34
Loser (just to understand)
Acid
35
Gainer (just to understand)
Base
36
If the question is looking for the conjugate acid, what must the substances in the questions be?
Bases
37
If the question is looking for the conjugate acid then the substances in the question must be bases so …...
Accept a proton onto each to get the answer
38
If the question is looking for the conjugate base, what must the substances in the questions be?
Acids
39
If the question is looking for the conjugate acid then the substances in the question must be acids so …...
Donate a proton from each to get the answer.
40
What happens to acids when they are placed in solutions?
They split up into their ions, hydrogens ions and anions.
41
What does the anion produced in a solution depend on?
The acid involved
42
When acids are placed in solutions they split up into their ions, hydrogen ions and anions. What is this known as?
Dissociation
43
What does the number of dissociation depend on?
Whether the acids are monobasic, dibasic or tribasic.
44
How many equations do monobasic acids have for their dissociation?
One
45
How many equations do dibasic acids have for their dissociation?
Two
46
How many equations do tribasic acids have for their dissociation?
Three
47
1st dissociation of H₂SO₄ (dibasic)
H₂SO₄ + H₂O ⇾ HSO₄- + H₃O⁺
48
2nd dissociation of H₂SO₄ (dibasic)
HSO₄- + H₂O ⇾ SO₄²- + H₃O⁺
49
Example of monobasic acids HCl + H₂O ⇾
HCl + H₂O ⇾ Cl- + H₃O⁺
50
Acid + Metal ⇾
Salt + H₂
51
Acid + metal oxide / hydroxide ⇾
Salt + H₂O
52
Acid + Metal carbonate / hydrogencarbonate ⇾
Salt + H₂O + CO₂
53
Salt + H₂ ←
Acid + Metal
54
Salt + H₂O ←
Acid + metal oxide / hydroxide
55
Salt + H₂O + CO₂ ←
Acid + Metal carbonate / hydrogencarbonate
56
Alkalis react with acids to produce ……….
A salt and water.
57
Alkalis react with acids to produce a salt and water, what is this called?
A neutralisation reaction.
58
What happens in a neutralisation reaction?
The H⁺ from the acid reacts with the OH- from the alkali to form H₂O which is neutral.
59
Define salts
A salt is formed when the H⁺ of the acid is replaced by a metal ion or NH₄⁺ (ammonium ion).
60
What is the non-metal part of a salt called?
A radical or complex ion.
61
What will happen when some acids are placed in solution?
All of the molecules will dissociate.
62
What happens when acids are placed in solution?
They dissociate into their ions.
63
What happens when other acids are placed into the solution?
Only some of the molecules will dissociate, the remaining molecules will remain undissociated.
64
What is the degree to which acids dissociate called?
The 'strength' of the acid.
65
Will you be able to identify the strength of an acid or base by looking at it?
No ones on course must be learnt.
66
Define a strong acid
A strong acid is an acid that fully dissociates in solution and is a good proton donor.
67
What happens to all the acid molecules in a strong acid?
They split up into hydrogen ions and anions.
68
What are strong acids (referring to donors)
Good proton donors.
69
What type of conjugate base does a strong acid have?
A weak conjugate base
70
Give three examples of strong acids (fully ionise in solution)
- HCl
- HNO₃
- H₂SO₄
71
Define a weak acid.
A weak acid is an acid that is a poor proton donor and only slightly dissociated in solution.
72
How many of the acid molecules in weak acids, split up into hydrogen ions and anions?
Only some
73
What are weak acids (referring to donors)
Poor proton donors.
74
Give an example of a weak acid.
CH₃COOH - ethanoic acid
75
In a dilute solution, what is the amount of molecules of ethanoic acid split into ions.
One molecule of ethanoic acid in a hundred splits into ions.
76
What type of conjugate base do weak acids have?
Strong conjugate base.
77
A strong base is a ……… ……….. of protons.
Good acceptor
78
A weak base is a ……… ……….. of protons.
Poor acceptor
79
Give 6 household examples of acids and bases.
1. Ethanoic acid in vinegar
2. Citric acid in citrus fruits such as oranges and lemons
3. Carbonic acid in fizzy drinks
4. Ammonia solution in cleaning agents
5. Magnesium hydroxide in indigestion remedies
6. Zinc oxide in skin creams
80
Why is ammonia solution in cleaning agents?
As it is very caustic and will burn through the dirt.
81
Example of magnesium hydroxide in indigestion remedies.
Milk of Magnesia
82
Define the term strong acid. (L.C)
An acid that fully dissociates in solution and is a good proton donor.
83
Define the term dibasic acid. (L.C)
A dibasic acid produces two H⁺ ions in solution e.g. H₂SO₄.
84
Define acid (Bronsted-Lowry theory) (L.C)
An acid is a proton (H⁺) donor.
85
Define conjugate pair (Bronsted-Lowry theory) (L.C)
Two substances that differ by one proton.
86
What is the conjugate acid of the sulfate ion? (L.C)
N
87
What is the conjugate base of nitric acid :
| 4HNO₃ → 2H₂O + 4NO₂ + O₂ (L.C)
NO₃-
88
What is the conjugate acid of HS- ? (L.C)
n
89
What is the conjugate acid of SO₃²- ? (L.C)
n
90
Define acid according to the Bronsted-Lowry theory.(L.C)
An acid is a proton (H⁺) donor.
91
Define base according to the Bronsted-Lowry theory . (L.C)
A base is a proton (H⁺) acceptor.
92
Identify the acid, and conjugate acid in the following system: H₂S + O²- ⇾ OH- + SH- (L.C)
H₂S (both are acids and both are conjugate bases)
| OH-
93
Write (i) the conjugate acid and (ii) the conjugate base of HPO₄²-. (L.C)
Conjugate acid - H₂PO₄-
| Conjugate base - PO₄³-
94
Identify one species acting as an acid, and also identify its conjugate base in the following system : H₂F⁺ + Cl- ⇌ HCl + HF
(must match correct one)
Acid - H₂F⁺ / HCl
Conjugate base - HF / Cl-
95
Identify one species acting as an acid, and also identify its conjugate base in the following system : H₂F⁺ + Cl- ⇌ HCl + HF (L.C)
(must match correct one)
Acid - H₂F⁺ / HCl
Conjugate base - HF / Cl-
96
Distinguish between a strong acid and a weak acid. (L.C)
Strong acid - an ad that fully dissociates in solution and is a good proton donor.
Weak acid - an acid that is a poor proton donor and only slightly dissociated in solution.
97
Distinguish between a strong acid and a weak acid. (L.C)
Strong acid - an acid that fully dissociates in solution and is a good proton donor.
Weak acid - an acid that is a poor proton donor and only slightly dissociated in solution.
98
Define acid according to the theory of Bronsted-Lowry. (L.C)
An acid is a proton (H⁺) donor.
99
Distinguish between a strong acid and a weak acid. (L.C)
Strong acid - an acid that fully dissociates in solution and is a good proton donor.
Weak acid - an acid that is a poor proton donor and only slightly dissociated in solution.
100
Identify the two conjugate pairs in the following dissociation of nitrous acid (HNO₂): HNO₂ + H₂O ⇌ NO₂- + H₃O⁺
- HNO₂ and NO₂-
| - H₂O and H₃O⁺
101
Define acid according to the Bronsted-Lowry theory. (L.C)
An acid is a proton (H⁺) donor.
102
Define conjugate acid according to the Bronsted-Lowry theory. (L.C)
A base plus a H⁺ ion.
103
Distinguish between a strong acid and a weak acid. (L.C)
Strong acid - an acid that fully dissociates in solution and is a good proton donor.
Weak acid - an acid that is a poor proton donor and only slightly dissociated in solution.
104
Define an acid in terms of the Bronsted-Lowry theory. (L.C)
An acid is a proton (H⁺) donor.
105
What is a conjugate pair? (L.C)
Two substances that differ by one proton.
106
What is the conjugate base of HX? (L.C) more there
N
107
How do strong acids differ from weak acids in their behaviour in water according to the Arrhenius' theory. (L.C)
Strong : Almost completely dissociated to give hydrogen ions (H⁺) in solution.
Weak : Only slightly dissociated to give hydrogen ions (H⁺) in solution.
108
What is the conjugate base of (i) sulfuric acid, (ii) the weak acid of HA? Which of these conjugate bases is stronger? Explain (L.C)
(i) HSO₄-
(ii) A-
(iii) A-
(iv) Conjugate base of a weak acid.
109
Explain, by giving a balanced equation for its dissociation in water, that the conjugate base of sulfuric acid is itself an acid. (L.C)
HSO₄- + H₂O ⇾ SO₄²- + H₃O⁺
110
How do strong acids differ from weak acids in their behaviour in water according to the Bronsted-Lowry theory. (L.C)
Strong : good proton (H⁺) donor.
| Weak : poor proton (H⁺) donor
111
Did Arrhenius theory include non-polar organic solvents?
No
