06-07 Formulae, Equations and the Mole, Set B To print: Ctrl + P, paper A4, margins Default.
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06-07

Formulae, Equations and the Mole

Set BExam practice
Name
Time 55 minutes
Total 29 marks

Use a copy of the Periodic Table where you need one. One mole of any gas occupies 24 dm3 at room temperature and pressure.

A

Multiple choice

9 marks
1

Sodium hydrogencarbonate decomposes on heating. 2NaHCO3 → Na2CO3 + CO2 + H2O. In an experiment, 5.0 mol of sodium hydrogencarbonate was heated. What is the volume of carbon dioxide evolved, at room temperature and pressure?

A24 dm3
B36 dm3
C48 dm3
D60 dm3
Answer [1]

Source: 2023 PLMGS Sec 3 End-of-Year P1 Q24

2

The atomic number of ruthenium is 44. One of the oxides of ruthenium is a black solid, X. 5.79 g of X contains 1.39 g of oxygen. What is the empirical formula of X?

ARu2O3
BRuO
CRuO2
DRu2O
Answer [1]

Source: 2023 PLMGS Sec 3 End-of-Year P1 Q25

3

Which contains the greatest mass of solute?

A100 cm3 of 1.00 mol/dm3 sodium hydroxide, NaOH
B500 cm3 of 0.05 mol/dm3 sulfuric acid, H2SO4
C1.00 dm3 of 0.10 mol/dm3 potassium hydroxide, KOH
D2.00 dm3 of 0.01 mol/dm3 hydrochloric acid, HCl
Answer [1]

Source: 2023 PLMGS Sec 3 End-of-Year P1 Q27

4

The forward reaction for the Haber process is N2(g) + 3H2(g) → 2NH3(g). 15 cm3 of nitrogen was added to 60 cm3 of hydrogen in a container. What is the total volume of gas remaining in the container after the reaction is complete?

A30 cm3
B40 cm3
C45 cm3
D105 cm3
Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q25

5

Carbon monoxide reacts with oxygen to form carbon dioxide: 2CO(g) + O2(g) → 2CO2(g). In this reaction, 3 moles of carbon monoxide and 2 moles of oxygen are mixed. When the reaction is complete, there will be

A0.5 mole of oxygen unreacted.
B1 mole of carbon monoxide unreacted.
C2 moles of carbon dioxide produced.
D4 moles of carbon dioxide produced.
Answer [1]

Source: SJI 2020 Year 3 End-of-Year P1 Q17

6

In a titration, 26.4 cm3 of 0.2 mol/dm3 aqueous calcium hydroxide was required to completely neutralise 19.0 cm3 of dilute hydrochloric acid. What is the concentration of the acid used?

A0.28 mol/dm3
B0.36 mol/dm3
C0.56 mol/dm3
D0.84 mol/dm3
Answer [1]

Source: 2023 HYSS Sec 3 End-of-Year P1 Q18

7

20.0 cm3 of 0.100 mol/dm3 potassium hydroxide is completely reacted with 20.0 cm3 of sulfuric acid solution. What is the concentration of potassium ions in the resultant solution?

A0.050 mol/dm3
B0.100 mol/dm3
C0.250 mol/dm3
D0.300 mol/dm3
Answer [1]

Source: SJI 2020 Year 3 End-of-Year P1 Q16

8

On adding 53 g of impure sodium carbonate, Na2CO3 (Mr = 106), to excess hydrochloric acid, 3.0 dm3 of CO2 was evolved at room temperature and pressure. What is the percentage purity of the sodium carbonate?

A25%
B50%
C75%
D100%
Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q28

9

Zinc blende is mainly zinc sulfide, ZnS. When it is burnt in air: 2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g). 194 g of an impure zinc blende sample is burnt in excess oxygen to produce 43.2 dm3 of sulfur dioxide. What is the percentage purity of zinc sulfide in the sample?

A80.0%
B85.0%
C90.0%
D95.0%
Answer [1]

Source: SJI 2020 Year 3 End-of-Year P1 Q18

B

Structured questions

20 marks
10

Methane, CH4, is a commonly used gas for household cooking. 20 cm3 of methane and 60 cm3 of oxygen are reacted to form carbon dioxide and water as the only products.

(a)
Write a balanced chemical equation with state symbols for the reaction of methane and oxygen.
[2]
(b)
Determine which is the limiting reagent for the reaction in (a).
[3]
(c)
Calculate the total volume of gas remaining at the end of the reaction at room temperature and pressure.
[2]
(d)
In reality, the percentage yield of carbon dioxide produced is only 70%. Calculate the volume of CO2 produced.
[1]

Source: SJI 2020 Year 3 End-of-Year P2 A4

11

30.0 cm3 of 0.80 mol/dm3 nitric acid was reacted with 10 g of magnesium.

Calculate the mass of magnesium nitrate produced.
[3]

Source: 2023 GESS Sec 3 End-of-Year P2 B12(a)

12

Sodium hydride, NaH, is an ionic compound. In a reaction, 0.24 g of sodium hydride was reacted with 1.8 cm3 of water to form sodium hydroxide solution and hydrogen gas at r.t.p.

(a)
Write a balanced chemical equation for the above reaction.
[1]
(b)
Given that the density of water is 1 g/cm3, determine the limiting reactant of this reaction and hence calculate the number of moles of sodium hydroxide formed.
[3]

Source: 2024 SMSS Sec 3 End-of-Year P2 Q5(b)

13

A common antacid is magnesium hydroxide, Mg(OH)2, a base that is slightly soluble in water. 25.0 cm3 of a saturated solution of magnesium hydroxide required 27.60 cm3 of 0.220 mol/dm3 dilute hydrochloric acid for complete neutralisation.

(a)
(i)
Write a balanced chemical equation for the reaction between magnesium hydroxide and dilute hydrochloric acid.
[1]
(ii)
Using your equation in (a)(i), calculate the concentration, in mol/dm3, of the saturated magnesium hydroxide solution.
[2]
(b)
Calculate the mass of magnesium hydroxide dissolved in 1.00 dm3 of the saturated magnesium hydroxide solution.
[1]
(c)
Given that a 10.0 g tablet of antacid contains 100% magnesium hydroxide by mass, calculate the minimum volume of water needed to fully dissolve the tablet.
[1]

Source: 2024 CHS Sec 3 End-of-Year Section B Q7