8-18.

1 Revision test [66 marks]

1. [Maximum mark: 1] 22N.1.sl.TZ0.19

−3
Equal volumes of 0.10 mol dm weak acid and strong acid are titrated with
0.10 mol dm−3 NaOH solution. Which of these is the same for the two acids?

A. Initial pH

B. Heat evolved in the neutralization

C. Volume of NaOH for complete neutralization

D. Initial electrical conductivity [1]

2. [Maximum mark: 1] 22N.1.sl.TZ0.20

Which species has the weakest conjugate base?

A. HCl

B. NH4+

C. HCO3−

D. H2O [1]
3. [Maximum mark: 1] 22N.1.hl.TZ0.23
Which of these changes would shift the equilibrium to the right?

[Co(H2O)6]2+ (aq) + 4Cl− (aq) ⇌ [CoCl4]2− (aq) + 6H2O (l)

I. Addition of 0.01 M HCl

II. Addition of concentrated HCl
III. Evaporation of water

A. I and II only

B. I and III only

C. II and III only

D. I, II and III [1]

4. [Maximum mark: 1] 22N.1.hl.TZ0.26

Which solutions will form a buffer when mixed?

A. 50 cm3 of 1.0 mol dm−3 HCl and 50 cm3 of 1.0 mol dm−3 NaOH

B. 50 cm3 of 1.0 mol dm−3 CH3COOH and 50 cm3 of 1.0 mol dm−3 NaOH

C. 50 cm3 of 1.0 mol dm−3 CH3COOH and 100 cm3 of 1.0 mol dm−3 NaOH

D. 100 cm3 of 1.0 mol dm−3 CH3COOH and 50 cm3 of 1.0 mol dm−3 NaOH [1]
5. [Maximum mark: 1] 22N.1.hl.TZ0.27
Which species can act both as a Lewis acid and a Lewis base?

A. H2O

B. NH4+

C. Cu2+

D. CH4 [1]
6. [Maximum mark: 18] 22N.2.sl.TZ0.1
Ammonium nitrate, NH4NO3, is used as a high nitrogen fertilizer.

Cold packs contain ammonium nitrate and water separated by a membrane.

Solid ammonium nitrate can decompose to gaseous dinitrogen monoxide and

liquid water.

(a) Calculate the percentage by mass of nitrogen in ammonium nitrate.

Use section 6 of the data booklet. [1]

(b) State, with a reason, whether the ammonium ion is a Brønsted-

Lowry acid or base. [1]

(f.iv) Deduce the Lewis (electron dot) structure and shape for dinitrogen
monoxide showing nitrogen as the central atom.

[2]

(f.ii) Calculate the volume of dinitrogen monoxide produced at STP

when a 5.00 g sample of ammonium nitrate decomposes. Use
section 2 of the data booklet. [2]

(f.iii) Calculate the standard enthalpy change, ΔH ⦵ , of the reaction. Use

section 12 of the data booklet.

⦵
ΔH
f
ammonium nitrate = −366 kJ mol−1
 ⦵
ΔH
f
dinitrogen monoxide = 82 kJ mol−1
[2]

(f.i) Write the chemical equation for this decomposition. [1]

(e.ii) The change in enthalpy when ammonium nitrate dissolves in water

is 25.69 kJ mol−1. Determine the mass of ammonium nitrate in the
cold pack using your answer obtained in (e)(i) and section 6 of the
data booklet.

If you did not obtain an answer in (e)(i), use 3.11 × 103 J, although
this is not the correct answer. [2]

(c) Deduce the Lewis (electron dot) structure for the nitrate anion. [1]

(e.i) The mass of the contents of the cold pack is 25.32 g and its initial
temperature is 25.2 °C. Once the contents are mixed, the temperature
drops to 0.8 °C.

Calculate the energy, in J, absorbed by the dissolution of ammonium

nitrate in water within the cold pack. Assume the specific heat
capacity of the solution is 4.18 J g−1 K−1. Use section 1 of the data
booklet. [1]

(e.iv) The cold pack contains 9.50 g of ammonium nitrate. Calculate the
percentage error in the experimentally determined mass of
ammonium nitrate obtained in (e)(ii).

If you did not obtain an answer in (e)(ii), use 6.55 g, although this is
not the correct answer. [1]

(d) Calculate the pH of an ammonium nitrate solution with [H3O+] =

1.07 × 10−5 mol dm−3. Use section 1 of the data booklet. [1]

(e.iii) The absolute uncertainty in mass of the contents of the cold pack is
±0.01 g and in each temperature reading is ±0.2 °C. Using your
answer in (e)(ii), calculate the absolute uncertainty in the mass of
ammonium nitrate in the cold pack.
If you did not obtain an answer in (e)(ii), use 6.55 g, although this is [3]
not the correct answer.
7. [Maximum mark: 10] 22N.2.hl.TZ0.5
Lignite, a type of coal, contains about 0.40 % sulfur by mass.

(a) Calculate the amount, in mol, of sulfur dioxide produced when

500.0 g of lignite undergoes combustion.

S (s) + O2 (g) → SO2 (g) [2]

(b) Write an equation that shows how sulfur dioxide can produce acid
rain. [1]

(c) Deduce the Lewis (electron dot) structure for sulfur dioxide. [1]

(d) Sodium thiosulfate reacts with hydrochloric acid as shown:

Na2S2O3 (aq) + 2HCl (aq) → S (s) + SO2 (aq) + 2NaCl (aq) + H2O (l)

The precipitate of sulfur makes the mixture cloudy, so a mark

underneath the reaction mixture becomes invisible with time.

Suggest two variables, other than concentration, that should be

controlled when comparing relative rates at different temperatures. [2]

(e) Discuss two different ways to reduce the environmental impact of

energy production from coal.
 [2]

(f ) SF4Cl2 can form two isomers, one which is polar and another non-
polar. Deduce the 3-dimensional representations of both isomers of
SF4Cl2.

[2]

8. [Maximum mark: 1] 22M.1.sl.TZ1.20

Which 0.01 mol dm–3 aqueous solution has the highest pH?

A. HCl

B. H2SO4

C. NaOH

D. NH3 [1]
9. [Maximum mark: 1] 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?

[1]
10. [Maximum mark: 1] 22M.1.sl.TZ2.20
What is the strongest acid in the equation below?

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

A. H3AsO4

B. H2O

C. H2AsO4−

D. H3O+ [1]
11. [Maximum mark: 15] 22M.2.sl.TZ1.2
Ammonia, NH3, is industrially important for the manufacture of fertilizers,
explosives and plastics.

Ammonia is produced by the Haber–Bosch process which involves the

equilibrium:

N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g)

The effect of temperature on the position of equilibrium depends on the

enthalpy change of the reaction.

Ammonia is soluble in water and forms an alkaline solution:

NH3 (g) + H2O (l) ⇌ NH4+ (aq) + HO– (aq)

(a) Draw arrows in the boxes to represent the electron configuration of

a nitrogen atom.

[1]

(b) Draw the Lewis (electron dot) structure of the ammonia molecule. [1]

(c(i)) Deduce the expression for the equilibrium constant, Kc, for this
equation. [1]

(e(iii)) Calculate the concentration of hydroxide ions in an ammonia

solution with pH = 9.3. Use sections 1 and 2 of the data booklet. [1]

(c(iii)) State how the use of a catalyst affects the position of the
equilibrium.
 [1]

(d(i)) Determine the enthalpy change, ΔH, for the Haber–Bosch process, in
kJ. Use Section 11 of the data booklet. [3]

(c(ii)) Explain why an increase in pressure shifts the position of equilibrium

towards the products and how this affects the value of the
equilibrium constant, Kc. [2]

(d(ii)) Calculate the enthalpy change, ΔH⦵, for the Haber–Bosch process, in
kJ, using the following data.

⦵
ΔH
f
(NH3 )= −46. 2 kJ mol
−1
. [1]

(e(ii)) Determine the concentration, in mol dm–3, of the solution formed

when 900.0 dm3 of NH3 (g) at 300.0 K and 100.0 kPa, is dissolved in
water to form 2.00 dm3 of solution. Use sections 1 and 2 of the data
booklet. [2]

(d(iii)) Suggest why the values obtained in (d)(i) and (d)(ii) differ. [1]

(e(i)) State the relationship between NH4+ and NH3 in terms of the
Brønsted–Lowry theory. [1]
12. [Maximum mark: 13] 22M.2.sl.TZ2.3
Sulfur trioxide is produced from sulfur dioxide.

2SO2 (g) + O2 (g) ⇌ 2SO3 (g) ΔH = −196 kJ mol−1

The reaction between sulfur dioxide and oxygen can be carried out at different
temperatures.

Nitric acid, HNO3, is another strong Brønsted–Lowry acid. Its conjugate base is
the nitrate ion, NO3−

(a) Outline, giving a reason, the effect of a catalyst on a reaction. [2]

(b(i)) On the axes, sketch Maxwell–Boltzmann energy distribution curves

for the reacting species at two temperatures T1 and T2, where T2 > T1.

[3]

(b(ii)) Explain the effect of increasing temperature on the yield of SO3. [2]

(c(i)) State the product formed from the reaction of SO3 with water. [1]

(c(ii)) State the meaning of a strong Brønsted–Lowry acid. [2]

(d(ii)) Explain the electron domain geometry of NO3−. [2]

(d(i)) Draw the Lewis structure of NO3−. [1]

13. [Maximum mark: 1] 22M.1.hl.TZ1.27
In which set are the salts arranged in order of increasing pH?

A. HCOONH4 < KBr < NH4Br < HCOOK

B. KBr < NH4Br < HCOOK < HCOONH4

C. NH4Br < HCOONH4 < KBr < HCOOK

D. HCOOK < KBr < HCOONH4 < NH4Br [1]

14. [Maximum mark: 1] 22N.1.sl.TZ0.19

−3
Equal volumes of 0.10 mol dm weak acid and strong acid are titrated with
0.10 mol dm−3 NaOH solution. Which of these is the same for the two acids?

A. Initial pH

B. Heat evolved in the neutralization

C. Volume of NaOH for complete neutralization

D. Initial electrical conductivity [1]

© International Baccalaureate Organization, 2023