IB Questionbank

Updates to Questionbank

User interface language: English | Español

Date	May 2018	Marks available	2	Reference code	18M.2.sl.TZ1.5
Level	SL	Paper	2	Time zone	TZ1
Command term	Predict and Justify	Question number	5	Adapted from	N/A

Question

Limescale, CaCO₃(s), can be removed from water kettles by using vinegar, a dilute solution of ethanoic acid, CH₃COOH(aq).

Predict, giving a reason, a difference between the reactions of the same concentrations of hydrochloric acid and ethanoic acid with samples of calcium carbonate.

[2]

a.

Dissolved carbon dioxide causes unpolluted rain to have a pH of approximately 5, but other dissolved gases can result in a much lower pH. State one environmental effect of acid rain.

[1]

b.

Markscheme

slower rate with ethanoic acid

OR

smaller temperature rise with ethanoic acid

[H⁺] lower

OR

ethanoic acid is partially dissociated

OR

ethanoic acid is weak

Accept experimental observations such as “slower bubbling” or “feels less warm”.

[2 marks]

a.

Any one of:

corrosion of materials/metals/carbonate materials

destruction of plant/aquatic life

«indirect» effect on human health

Accept “lowering pH of oceans/lakes/waterways”.

[1 mark]

b.

Examiners report

[N/A]

a.

[N/A]

b.

Syllabus sections

Core » Topic 8: Acids and bases » 8.4 Strong and weak acids and bases

Show 35 related questions

17N.2.hl.TZ0.1e: Suggest why the enthalpy change of neutralization of CH3COOH is less negative than that of HCl.
18M.1.sl.TZ2.20: Which statement is correct? A. A strong acid is a good proton donor and has a strong...
18N.2.hl.TZ0.6a.i:
State the equation for the reaction of each substance with water.
22M.2.sl.TZ2.3c(ii): State the meaning of a strong Brønsted–Lowry acid.
16N.2.sl.TZ0.2a: Distinguish between a weak acid and a strong acid. Weak acid: Strong acid:
17M.1.sl.TZ1.20:
Which 1.0 mol $\,$ dm^–3 solution has the highest pH?

A. Ammonium chloride

B. Sulfuric acid

C. Sodium chloride

D. Ammonia
22M.1.sl.TZ2.20:
What is the strongest acid in the equation below?

H₃AsO₄ + H₂O $⇌$ H₂AsO₄⁻ + H₃O⁺ K_c = 4.5 × 10⁻⁴

A. H₃AsO₄

B. H₂O

C. H₂AsO₄⁻

D. H₃O⁺
22M.1.sl.TZ2.30:
20 cm³ of 1 mol dm⁻³ sulfuric acid was added dropwise to 20 cm³ of 1 mol dm⁻³ barium hydroxide producing a precipitate of barium sulfate.

H₂SO₄(aq) + Ba(OH)₂(aq) → 2H₂O (l) + BaSO₄(s)

Which graph represents a plot of conductivity against volume of acid added?
19N.2.sl.TZ0.4a(iii):
The dissociation of citric acid is an endothermic process. State the effect on the hydrogen ion concentration, [H⁺], and on the equilibrium constant, of increasing the temperature.
19N.2.sl.TZ0.4a(ii): The value of the equilibrium constant for the first dissociation at 298 K is 5.01 ×...
18M.2.hl.TZ1.5a:
Predict, giving a reason, a difference between the reactions of the same concentrations of hydrochloric acid and ethanoic acid with samples of calcium carbonate.
17M.2.hl.TZ2.8b.v:
State a technique other than a pH titration that can be used to detect the equivalence point.
22M.2.hl.TZ2.6d(ii): State the meaning of a strong Brønsted–Lowry acid.
18N.2.sl.TZ0.6a:
State the equation for the reaction of each substance with water.
18N.1.sl.TZ0.20:
What is the order of increasing pH for the following solutions of the same concentration?

A. HCl (aq) < NH₃ (aq) < NaOH (aq) < CH₃COOH (aq)

B. CH₃COOH (aq) < HCl (aq) < NH₃ (aq) < NaOH (aq)

C. HCl (aq) < CH₃COOH (aq) < NH₃ (aq) < NaOH (aq)

D. NaOH (aq) < NH₃ (aq) < CH₃COOH (aq) < HCl (aq)
19M.2.hl.TZ1.5a:
Outline why ethanoic acid is classified as a weak acid.
17M.2.sl.TZ1.4c:
Hydrazine reacts with water in a similar way to ammonia. Deduce an equation for the reaction of hydrazine with water.
17M.3.hl.TZ2.4a:
Identify the other product formed.
19N.2.sl.TZ0.4b: Outline one laboratory methods of distinguishing between solutions of citric acid and...
19M.2.sl.TZ2.5a(i):
Distinguish between a weak and strong acid.

Weak acid:

Strong acid:
19N.3.sl.TZ0.16a:
Identify the compound responsible for the acidity of gastric juice, and state whether it is a strong or weak acid.
19N.2.hl.TZ0.4a(iii):
The dissociation of citric acid is an endothermic process. State the effect on the hydrogen ion concentration, [H⁺], and on K_a, of increasing the temperature.
19N.2.hl.TZ0.4a(ii): The value of Ka at 298 K for the first dissociation is 5.01 × 10−4. State, giving a reason,...
19N.2.hl.TZ0.4b: Outline two laboratory methods of distinguishing between solutions of citric acid and...
17M.2.sl.TZ1.4d:
Outline, using an ionic equation, what is observed when magnesium powder is added to a solution of ammonium chloride.
19M.2.sl.TZ1.5a:
Outline why ethanoic acid is classified as a weak acid.
18M.2.sl.TZ2.2b.ii:
State and explain the effect on the rate of reaction if ethanoic acid of the same concentration is used in place of hydrochloric acid.
17M.3.sl.TZ2.14b.ii:
Describe how large amounts of CO₂ could reduce the pH of the ocean using an equation to support your answer.
19M.2.hl.TZ2.5a(i):
Distinguish between a weak and strong acid.

Weak acid:

Strong acid:
21M.2.sl.TZ1.2b(ii):
Saturated aqueous hydrogen sulfide has a concentration of 0.10 mol dm⁻³ and a pH of 4.0. Demonstrate whether it is a strong or weak acid.
20N.1.sl.TZ0.20:
Which of these acids has the weakest conjugate base?

A.   $HCl$

B.   ${CH}_{3} COOH$

C.   ${NH}_{4} Cl$

D.   $C_{6} H_{5} COOH$
20N.2.sl.TZ0.1c(i): Hypochlorous acid is considered a weak acid. Outline what is meant by the term weak acid.
20N.2.hl.TZ0.1c(i): Hypochlorous acid is considered a weak acid. Outline what is meant by the term weak acid.
17M.3.sl.TZ2.14b.i:
Oceans can act as a carbon sink, removing some CO₂(g) from the atmosphere.

CO₂(g) $\rightleftharpoons$ CO₂(aq)

Aqueous carbon dioxide, CO₂(aq), quickly reacts with ocean water in a new equilibrium reaction. Construct the equilibrium equation for this reaction including state symbols.
21N.1.sl.TZ0.20: Which ions are present in an aqueous solution of Na2CO3? I. HCO3−II. OH−III. CO32− A. I...

Hide related questions

Core » Topic 8: Acids and bases