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
Using your knowledge of the Brønsted-Lowry theory, which of the following correctly describes ammonia?
neutral
acid
base
amphoteric
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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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Which of the following ions or compounds is amphiprotic?
P4O10
PO43−
HCO3−
Al2O3
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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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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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Copper(II) sulfate can be made by the reaction between dilute sulfuric acid and which of the following?
I and II only
I and III only
II and III only
I, II and III
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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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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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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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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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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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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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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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Which is the correct expression for the ionic product of water at 25 ℃ is
H2O (l) ⇌ H+ (aq) + OH- (aq)
Kw = [H+][OH-]
1 x 10-14 mol2 dm-6
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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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90 cm3 of water is added to 10 cm3 of sulfuric acid with a pH of 2. What is the new pH of the acid?
1
3
5
7
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Which of the following is true about weak acids?
I and II only
I and III only
II and III only
I, II and III
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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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Four solutions, K, L, M and N have the following properties
K: pH= 8 L: [H+] = 1 x 10-3 mol dm-3 M: pH= 5 N: [H+] = 1 x 10-7 mol dm-3
What is their correct order of increasing acidity?
K < L < M < N
N < L < M < K
K < N < M < L
N < M < L < K
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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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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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Which 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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Which mixture cannot act as a buffer?
CH3COOH (aq) and CH3COONa (aq)
CH3CH2COOH (aq) and CH3CH2COONa (aq)
HNO3 (aq) and NaOH (aq)
NH3 (aq) and NH4Cl (aq)
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The hydrolysis of ammonium chloride takes place via the following reaction.
NH4+ + H2O → H3O+ + NH3
Which of the following is correct?
The resultant pH is above 7
The resultant pH is 7
The resultant pH is below 7
Ammonium chloride is insoluble
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Which of the following is the acid dissociation, Ka, constant for ethanoic acid?
CH3COOH
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At the same concentration, which acid would have the lowest pH?
C6H5COOH Ka = 6.3 x 10-5 mol dm-3
HCOOH Ka = 1.8 x 10-4 mol dm-3
HCN Ka = 4.9 x 10-10 mol dm-3
CH3CH2COOH Ka = 1.4 x 10-5 mol dm-3
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The pKb value of ethylamine is 3.35 at 298 K. What is the value of the pKa ethylammonium ion?
2.99 x 10–14
10.65
4.18
2.24 x 10–10
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Which of the following is the correct equation to calculate the concentration of hydroxide ions?
-log [H+]
14 - pOH
10-pOH
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Which shows the correct relationship between Kw, Ka and Kb?
Kw = Ka + Kb
Kw = Ka x Kb
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The typical reactions of dilute acids include them being able to react with
I and II only
I and III only
II and III only
I, II and III
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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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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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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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Potassium hydrogenphosphate has the formula K2HPO4 . What is the conjugate base of this compound?
H2PO4-
KHPO42-
PO43-
KH2PO4
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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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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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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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Which oxides react with calcium oxide?
I and II only
I and III only
II and III only
I, II and III
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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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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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Calculate the pH of a solution of NaOH of concentration 0.001 mol dm-3
1
3
11
13
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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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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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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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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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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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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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Which row shows the correct properties of 0.1 mol dm-3 LiOH?
|
pH |
Electrical conductivity |
Universal indicator colour |
A |
10 |
poor |
green |
B |
13 |
good |
purple |
C |
10 |
poor |
red |
D |
13 |
poor |
blue |
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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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Which of the following statements are correct for a titration between 0.10 mol dm-3 propanoic acid and 0.10 mol dm-3 potassium hydroxide?
The equivalence point will be at pH 7
The salt formed will hydrolyse to form an acidic salt
The salt formed will be CH3COOK
At half equivalence point [CH3CH2COOH (aq)] = [CH3CH2COO- (aq)]
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Which of the following statements about indicators are correct?
I and II only
I and III only
II and III only
I, II and III
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Which statement about buffer solutions is not correct?
A buffer resists small changes in pH
A buffer can be formed from sodium hydroxide and an excess of ethanoic acid
The pH during a titration between a strong acid and weak base changes slowly in the buffer region
When a strong acid is added to a buffer, hydrogen ions react with salt ions
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The pH range of four different indicators are:
Indicator |
pKa |
Methyl orange |
3.7 |
Phenolphthalein |
9.6 |
Phenol red |
7.9 |
Bromothymol blue |
7.0 |
Which indicator would be suitable for a titration involving hydrochloric acid and ammonia?
Methyl orange
Phenolphthalein
Phenol red
Bromothymol blue
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The table shows the pKa and Ka values for four acids
Acid |
pKa |
Ka |
Butanoic Acid |
- |
1.51 x 10-5 |
Nitrous acid |
3.1 |
- |
Lactic acid |
3.4 |
- |
Phenol |
- |
1 x 10-10 |
Which of the following is the correct order of increasing strength of the acids
Phenol < butanoic acid < lactic acid < nitrous acid
Nitrous acid < lactic acid < butanoic acid < phenol
Nitrous acid < butanoic acid < phenol < lactic acid
Phenol < lactic acid < butanoic acid < nitrous acid
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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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Which of the following statements about conjugate acid and base pairs are correct?
The conjugate base for ethanoic acid is CH3COO-
I and II only
I and III only
II and III only
I, II and III
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What is the correct expression to use to determine the pH of butanoic acid with concentration of 0.75 mol dm-3?
The Ka of butanoic acid at 298 K is 1.51 x 10-5 mol dm-3
4.95
2.47
0.12
4.82
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What is the correct expression for the base dissociation constant, Kb, for propylamine?
Kb =
Kb =
Kb =
Kb =
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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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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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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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Which of the following substances can be used to prepare magnesium sulfate by a neutralization reaction with dilute sulfuric acid?
I and II only
I and III only
II and III only
I, II and III
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Phosphoric acid is a polyprotic acid and can produce amphiprotic species when it dissociates. Which of the following species is amphiprotic?
I and II only
I and III only
II and III only
I, II and III
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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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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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Which of the following solutions will react with a strip magnesium ribbon?
Sodium hydrogencarbonate
Sodium hydrogensulfate
Ammonia
Limewater
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Which substance reacts with ammonia but is not a Brønsted–Lowry acid?
HCl
CH3COOH
BF3
CF3COOH
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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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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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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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If the pH of two acids, X and Y, are pH 1 and pH 2 respectively, which of the following is true?
I and II only
I and III only
II and III only
I, II and III
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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?
I and II only
I and III only
II and III only
I, II and III
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Which row shows the correct colours for two common indicators used in acid-alkali titrations?
phenolphthalein |
methyl orange |
|
colour in acid |
colour in alkali |
colour in acid |
colour in alkali |
A |
pink |
colourless |
yellow |
red |
B |
colourless |
pink |
yellow |
red |
C |
pink |
colourless |
red |
yellow |
D |
colourless |
pink |
red |
yellow |
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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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What is the number of moles of barium hydroxide in a 100 cm3 solution with a pH of 11 at 25 ℃?
(Kw = 1.00 x 10-14 mol2 dm-6 at 298 K)
1 10-11 mol
1 10-3 mol
0.5 10-3 mol
0.5 10-4 mol
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What is the pH of a solution made by adding 6.0 g of sodium hydroxide to 1 dm3 of water at 298K? (Mr NaOH = 40.00)
(Kw = 1.00 x 10-14 mol2 dm-6 at 298 K)
14.82
12.18
11.18
13.18
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Which values are correct for a solution that contains 0.056 g of KOH (Mr= 56) in 100 cm3 of water?
(Kw = 1.00 × 10-14 mol2 dm-6 at 298 K)
[H+] = 1.0 × 10-2 mol dm-3 and pH = 2.00
[OH-] = 1.0 × 10-2 mol dm-3 and pH = 2.00
[H+] = 1.0 × 10-12 mol dm-3 and pH = 12.00
[OH-] = 1.0 × 10-12 mol dm-3 and pH = 2.00
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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 10-3 mol dm-3
2.50 10-4 mol dm-3
2.50 10-5 mol dm-3
50.0 10-4 mol dm-3
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Which is true about the hydrogensulfate ion, HSO4-, found in acid rain?
I and II only
I and III only
II and III only
I, II and III
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Using appropriate molar ratios which mixtures could act as buffers?
I. NaOH and CH3COOH
II. CH3NH2 and CH3NH3Cl
III. NH3 and HCl
I and II only
I and III only
II and III only
I, II and III
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Which of the following salts would produce a solution with the highest pH if dissolved in water?
RbCl
CuSO4
KCl
Na2CO3
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The acid–base indicator bromophenol blue changes colour from yellow to blue over a pH range of 3.0–4.6. Which statement is correct?
I. The pKa is between 3.0 and 4.6
II. In a neutral solution [HIn] > [In-]
III. It is a suitable indicator for a strong acid, weak base titration
I and II only
I and III only
II and III only
I, II and III
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A titration was carried out using 25.00 cm3 of 0.100 mol dm-3 propanoic acid with 0.100 mol dm-3 sodium hydroxide. The indicator phenolphthalein was used to determine the equivalence point. Phenolphthalein has a pH range of 8.3 to 10.0.
If hydrochloric acid was used instead of propanoic acid of the same concentration, which of the following would remain the same?
The volume of base needed to reach the equivalence point
The pH at the equivalence point
The y intercept on the pH curve
The colour of the solution just before equivalence had been reached
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The table below shows data for the and values for some acids and bases at 298 K.
Acid | Ka | Base | pKb |
C5H6OH | 1.02 x 10-10 | (C2H5)3N | 3.25 |
O2NC6H4OH | 7.08 x 10-8 | C6H5NH2 | 9.13 |
Which two formulas represent the weakest acid and the weakest base in the table?
C5H6OH and C6H5NH2
O2NC6H4OH and C6H5NH2
O2NC6H4OH and (C2H5)3N
C5H6OH and (C2H5)3N
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The ionisation constant of water, Kw , at 40 °C is 2.92 x 10-14. Which of the following statements is correct?
pH = 7.0
The ionisation of water is exothermic
The pH of water is lower at 40 °C than at 25 °C
[H+] > [OH-] at 40 °C
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The Kb value for a base is 8.0 x 10-4 at 298 K. What is the pKa value for the conjugate acid at this temperature?
10
1.3 x 10-11
3.1
10.9
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The pKb value of HPO42- is 6.8. What is its conjugate acid and what is the Ka value?
Conjugate acid | Ka | |
A. | H2PO4- | 7.2 |
B. | H3PO4 | 7.2 |
C. | H3PO4 | 1.67 x 10-7 |
D. | H2PO4- | 6.3 x 10-8 |
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The strengths of four bases are:
What is the order of increasing base strength?
Ethanol < phenylamine < 3-nitrophenol < ethylamine
Ethanol < 3-nitrophenol < phenylamine < ethylamine
Ethylamine < 3-nitrophenol < phenylamine < ethanol
Ethylamine < phenylamine < 3-nitrophenol < ethanol
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