11 mark
Using your knowledge of the Brønsted-Lowry theory, which of the following correctly describes ammonia?
neutral
acid
base
amphoteric
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Syllabus Edition
First teaching 2023
First exams 2025
|
Proton Transfer Reactions (SL IB Chemistry)
Exam Questions
5 hours90 questions21 mark
In the Brønsted–Lowry theory of acids and bases, the difference between a conjugate acid and its conjugate base is the presence of which of the following?
a positive charge
a pair of electrons
a proton
a hydrogen atom
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31 mark
Which of the following ions or compounds is amphiprotic?
P4O10
PO43−
HCO3−
Al2O3
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41 mark
In the following reaction, identify which two species are acting as Brønsted–Lowry acids
H3PO4 (aq) + OH− (aq) ⇋ H2PO4− (aq) + H2O (l)
H2PO4− (aq) and OH− (aq)
H3PO4 (aq) and H2PO4− (aq)
H2PO4− (aq) and H2O (l)
H3PO4 (aq) and H2O (l)
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51 mark
Potassium hydrogen carbonate reacts vigorously with dilute sulfuric acid. Identify the correct formulas of the substances produced in the reaction
K2SO4 + H2O + CO2
K2SO4 + CO2
KSO4 + H2O + CO2
KSO4 + H2CO3
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61 mark
Copper(II) sulfate can be made by the reaction between dilute sulfuric acid and which of the following?
- Cu
- CuO
- CuCO3
I and II only
I and III only
II and III only
I, II and III
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71 mark
Which statement is correct for the following equation?
HSO4- (aq) + OH- (aq) ⇌ SO4- (aq) + H2O (l)
OH- and H2O are an acid and conjugate base pair
SO4- is acting as Brønsted–Lowry acid
HSO4- and SO4- are a base and conjugate acid pair
OH- and H2O are a base and conjugate acid pair
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81 mark
Which row shows the correct acid and base needed to make the salt specified?
|
Acid |
Base |
Salt |
|
|
A |
NaHCO3 |
SO2 |
Na2SO4 |
|
B |
HNO3 |
SO3 |
(NH4)2SO4 |
|
C |
H2SO4 |
ZnO |
ZnSO3 |
|
D |
H2SO4 |
NH4OH |
(NH4)2SO4 |
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91 mark
Which is a conjugate acid-base pair?
HCO3- (aq) + H2O (l) ⇌ CO32- (aq) + H3O+ (aq)
HCO3- / H3O+
HCO3- / CO32-
H2O / CO32-
HCO3- / H2O
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101 mark
Which coefficients balance the following acid-base equation?
Al(OH)3 (s) + HNO3 (aq) ⇌ Al(NO3)3 (aq) + H2O (l)
|
A |
3 |
1 |
3 |
1 |
|
B |
2 |
2 |
1 |
3 |
|
C |
1 |
3 |
1 |
3 |
|
D |
1 |
2 |
1 |
2 |
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111 mark
Four 1.0 M solutions of HCl, NH3, NaOH and CH3COOH have been mislabelled, but a student has a pH meter to test the pH of the solutions. Arrange the solutions in order of increasing pH:
HCl (aq) < NH3 (aq) < NaOH (aq) < CH3COOH (aq)
CH3COOH (aq) < HCl (aq) < NH3 (aq) < NaOH (aq)
HCl (aq) < CH3COOH (aq) < NH3 (aq) < NaOH (aq)
NaOH (aq) < NH3 (aq) < CH3COOH (aq) < HCl (aq)
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121 mark
Below are four statements about acid and bases. Which is the correct one?
Strong acids are good proton donors and have weak conjugate bases.
Strong bases are good proton donors and have weak conjugate acids.
Weak acids are poor proton acceptors and have strong conjugate bases.
Strong acids are good proton donors and have strong conjugate bases.
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131 mark
Which statement is correct about the action of weak acids and their conductivity?
Weak acids are proton donors and their solutions are good conductors.
Weak acids are proton donors and their solutions are poor conductors.
Weak acids are proton acceptors and their solutions are good conductors.
Weak acids are proton acceptors and their solutions are good conductors.
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141 mark
34.3 cm3 of 0.125 mol dm-3 sodium hydroxide solution reacts with 26.0 cm3 of sulfuric acid. What is the concentration of the acid?
0.16 mol dm–3
0.33 mol dm–3
0.08 mol dm–3
3.03 mol dm–3
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151 mark
Which of the following is true about weak acids?
- They are poor conductors of electricity
- They have a high pH
- They react with carbonates to produce carbon dioxide
I and II only
I and III only
II and III only
I, II and III
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161 mark
Which is true about 1.0 mol dm-3 solutions of weak and strong acids?
Magnesium will react with strong acids but not weak acids
Fewer moles of base are needed to neutralise weak acids
Sodium carbonate reacts more slowly with weak acids
Weak acids have a lower pH than strong acids
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171 mark
Two beakers contain solutions of hydrochloric acid at pH = 2 and pH = 4. How does the concentration of hydrogen ions compare in the two beakers?
Twice as large
Half as much
of the value
of the value
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181 mark
A sample of acid rain water is tested and found to be pH 4. How does its hydrogen ion concentration compare to pure water?
1000 times more concentrated
3 times more concentrated
1000 times less concentrated
3 times less concentrated
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19
1 mark
1 markWhich type of titration is indicated by the following pH curve?
Strong acid - strong base
Weak acid - weak base
Strong acid - weak base
Weak acid - strong base
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11 mark
The typical reactions of dilute acids include them being able to react with
- NaHCO3
- Mg
- Cu
I and II only
I and III only
II and III only
I, II and III
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21 mark
The following reaction occurs between concentrated sulfuric and nitric acids.
H2SO4 + HNO3 ⇋ H2NO3+ + HSO4-
Identify the two species which are acting as Brønsted–Lowry bases.
H2NO3+ and HSO4-
HNO3 and H2NO3+
H2SO4 and HSO4-
HNO3 and HSO4-
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31 mark
What role does each species play in the equilibrium below according to Brønsted-Lowry theory?
CH3COOH + HCl ⇌ CH3COOH2+ + Cl-
|
|
CH3COOH |
HCl |
CH3COOH2+ |
Cl- |
|
A |
acid |
base |
base |
acid |
|
B |
acid |
base |
acid |
base |
|
C |
base |
acid |
base |
acid |
|
D |
base |
acid |
acid |
base |
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41 mark
Perbromic acid, HBrO4 , is an example of a strong acid when dissolved in water. What is true about perbromic acid?
HBrO4 is largely found as molecules in the solution
HBrO4 solution reacts only with strong bases
HBrO4 is fully dissociated in solution
HBrO4 has a pH greater than 7
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51 mark
Potassium hydrogenphosphate has the formula K2HPO4 . What is the conjugate base of this compound?
H2PO4-
KHPO42-
PO43-
KH2PO4
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61 mark
For the equilibrium equation shown, which species are Brønsted-Lowry acids?
H3NSO3 (aq) + 2NH3 (aq) ⇌ HNSO32- (aq) + 2NH4+ (aq)
NH4+ and NH3
NH4+ and HNSO32-
H3NSO3 and HNSO32-
H3NSO3 and NH4+
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71 mark
Which would be formed when calcium oxide reacts with hydrochloric acid ?
Calcium chloride and carbon dioxide
Calcium chloride, hydrogen gas and water
Calcium, hydrogen gas and water
Calcium chloride and water
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81 mark
What is the sum of the coefficients when the following acid-base equation is balanced?
_HNO3 (aq) + _Mg(HCO3)2 (s) → _Mg(NO3)2 (aq) + _H2O (l) + _CO2 (g)
5
6
7
8
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91 mark
Which oxides react with calcium oxide?
- SO2
- NO2
- K2O
I and II only
I and III only
II and III only
I, II and III
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101 mark
Which row correctly describes the reaction specified?
|
|
Reaction |
Energy change |
|
A |
metal displacement |
endothermic |
|
B |
neutralisation |
exothermic |
|
C |
combustion |
endothermic |
|
D |
melting ice |
exothermic |
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111 mark
Determine which of the following solutions would be basic at 25 °C?
Kw = 1.0 × 10−14 mol2 dm-6
[H+] = 1.0 × 10−2 mol dm−3
[OH−] = 1.0 × 10−12 mol dm−3
solution of pH = 5.00
[H3O+] = 1.0 × 10−12 mol dm−3
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121 mark
Carbon dioxide reacts with water to form carbonic acid which can be represented in the following equation
CO2(g) + H2O(l) ⇋ H+(aq) + HCO3−(aq)
If the pressure is raised, what will happen to the position of equilibrium and the pH?
The equilibrium shifts to the right and pH increases
The equilibrium shifts to the right and pH decreases
The equilibrium shifts to the left and pH increases
The equilibrium shifts to the left and pH decreases
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131 mark
When comparing the separate reactions of 0.5 g magnesium metal with equal volumes and concentrations of hydrochloric acid and ethanoic acid you can say that the
Hydrochloric acid reacts faster than ethanoic acid as its pH is higher
More gas is produced with hydrochloric acid than with ethanoic acid
An equal volume of gas is produced with both hydrochloric acid and ethanoic acid.
Ethanoic acid reacts more slowly than hydrochloric acid because its pH is lower
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141 mark
A beaker contains 50 cm3 of sodium hydroxide solution and its pH is measured as 11.
If 450 cm3 of water is added to the beaker, what will be the new pH of the solution?
3
9
10
11
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151 mark
In the table below are the formulae of some acids and bases. Which row shows only weak acids and weak bases?
|
A |
CH3NH2 |
Ba(OH)2 |
HCOOH |
|
B |
CH3CH2COOH |
C6H5NH2 |
HCOOH |
|
C |
NH3 |
HNO3 |
CH3CH2COOH |
|
D |
NH3 |
KOH |
H2CO3 |
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161 mark
Three solutions of hydrochloric acid of different concentrations are shown below
X. 0.100 mol dm-3
Y. 0.001 mol dm-3
Z. 0.010 mol dm-3
If these solutions are arranged from lowest to highest pH, then the order is
X﹤ Y ﹤ Z
X﹤ Z ﹤ Y
Y﹤ X ﹤Z
Y﹤ Z ﹤ X
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171 mark
Which of the following statements is correct?
As temperature increases, the pH value of pure water decreases
As temperature decreases, the pH value of pure water decreases
The pH of water is unaffected by temperature
Pure water is not neutral
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181 mark
Equal volumes of hydrochloric acid of different concentrations are added to four beakers, A, B, C and D. Equal volumes of 1.0 mol dm-3 sodium hydroxide are then added to the beakers and the pH is measured.
|
Beaker |
A |
B |
C |
D |
|
pH |
1 |
5 |
7 |
13 |
Which beaker contains the most concentrated solution of hydrochloric acid?
Beaker A
Beaker B
Beaker C
Beaker D
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11 mark
Some species may be classified as amphiprotic, some as amphoteric and some as both. Which of the following applies to HPO42−?
Amphiprotic but not amphoteric
Amphoteric but not amphiprotic
Amphiprotic and amphoteric
Neither amphiprotic nor amphoteric
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21 mark
The aromatic compound phenol, C6H5OH, behaves as a weak acid, due the presence of a hydroxyl group on the benzene ring. What is the correct formula of the conjugate base formed when phenol dissociates?
C6H4--OH
C6H5-OH2+
C6H5-O-
C6H6+-OH
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31 mark
What is the sum of the coefficients when the following acid-base equation is balanced?
_Al2(CO3)3 (s) + _HNO3 (aq) ⇌ _Al(NO3)3 (aq) + _H2O (l) + _CO2 (g)
6
7
14
15
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41 mark
Which of the following substances can be used to prepare magnesium sulfate by a neutralization reaction with dilute sulfuric acid?
- Mg
- MgO
- MgCO3
I and II only
I and III only
II and III only
I, II and III
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51 mark
Phosphoric acid is a polyprotic acid and can produce amphiprotic species when it dissociates. Which of the following species is amphiprotic?
- HPO42−
- H2PO4−
- PO43−
I and II only
I and III only
II and III only
I, II and III
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61 mark
Use the following reactions to answer the question below:
H2O (l) + F- (aq) ⇌ HF (aq) + OH- (aq)
H2O (l) + HNO3 (aq) → H3O+ (aq) + NO3- (aq)
H2O (l) + CO2 (g) ⇌ H2CO3 (aq)
H2O (aq) + NH3 (aq) ⇌ NH4OH (aq)
Which of the following statements is true?
HNO3 and H2O both act as acids once
H2O is shown acting as a Bronsted-Lowry acid only
H2O reacts as an acid twice
H2O is shown as a diprotic acid
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71 mark
Which species are Bronsted-Lowry acids in the reaction shown?
H2PO4− (aq) + CN- (aq) ⇌ HCN (aq) + HPO42− (aq)
HCN and H2PO4−
HCN and CN-
H2PO4− and HPO42−
HCN and HPO42−
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81 mark
Which of the following solutions will react with a strip magnesium ribbon?
Sodium hydrogencarbonate
Sodium hydrogensulfate
Ammonia
Limewater
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91 mark
Which substance reacts with ammonia but is not a Brønsted–Lowry acid?
HCl
CH3COOH
BF3
CF3COOH
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101 mark
Which of the following statements is incorrect about 0.01 mol dm–3 CH3COOH?
the pH = 2
[H+] << 0.01 mol dm–3
[CH3COO–] is approximately equal to [H+]
CH3COOH is partially ionized
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111 mark
Two flasks contain two different acids labelled as HA and HB. A student measures the pH of each flask, and finds that they are pH 1 and pH 3 respectively. Which of the following statements is true?
HA is a stronger acid than HB
HB is a stronger acid than HA
The [H3O+] in the solution of HB is 3 times greater than the [H3O+] in the solution of HA.
The [H3O+] in the solution of HA is 100 times greater than the [H3O+] in the solution of HB.
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121 mark
Which of the following solutions will have the largest amount of H+ ions in moles?
20 cm3 of 2.0 mol dm−3 sulfuric acid
10 cm3 of 3.0 mol dm−3 nitric acid
80 cm3 of 0.5 mol dm−3 hydrochloric acid
40 cm3 of 1.0 mol dm−3 ethanoic acid
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131 mark
If the pH of two acids, X and Y, are pH 1 and pH 2 respectively, which of the following is true?
- X and Y could be strong or weak acids
- The concentration of [H+] ions in X is higher than in Y
- Acid X is stronger than acid Y
I and II only
I and III only
II and III only
I, II and III
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141 mark
A student has two flasks containing 150 cm3 of nitric acid, HNO3(aq) and ethanoic acid, CH3COOH(aq). She writes the following three statements in her notebook about the acids. Which of them are correct?
- HNO3 dissociates more than CH3COOH
- HNO3 conducts electricity better than CH3COOH
- more NaOH can be neutralized with HNO3 than CH3COOH
I and II only
I and III only
II and III only
I, II and III
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151 mark
In a titration, the equivalence point is reached when 23.70 cm3 of 0.02 mol dm-3 potassium hydroxide reacts with 0.03 mol dm-3 of sulfuric acid. What volume of acid is needed?
7.9 cm3
31.65 cm3
15.80 cm3
17.78 cm3
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161 mark
Acid rain can be up to 50 times more acidic than normal rain, which has a pH around 5.5. What is the approximate concentration of H+ in acid rain?
2.50
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10-3 mol dm-3 2.50
10-4 mol dm-3 2.50
10-5 mol dm-3 50.0
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10-4 mol dm-3
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171 mark
Which is true about the hydrogensulfate ion, HSO4-, found in acid rain?
- It is amphiprotic
- It is amphoteric
- Sulfur is in its highest oxidation state
I and II only
I and III only
II and III only
I, II and III
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