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

Formulae, Equations and the Mole

Set AFoundations
Name
Time 50 minutes
Total 27 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

Dimethylglyoxime has the chemical formula (CH3CNOH)2. How many atoms does one molecule of dimethylglyoxime contain?

A5
B8
C10
D16
Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q19

2

The formula of iridium sulfate is Ir2(SO4)3 and that of zinc hypochlorite is Zn(ClO)2. What is the formula of iridium hypochlorite?

AIr2(ClO)2
BIr2(ClO)3
CIrClO
DIr(ClO)3
Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q20

3

A piece of zinc strip is burnt in oxygen to form zinc oxide. Which of the following chemical equations is correct?

A2Zn + O2 → 2ZnO
B2Zn + O → Zn2O
CZn + O2 → ZnO2
DZn + O → ZnO
Answer [1]

Source: 2023 XMS Sec 3 WA2 Q3

4

Which chemical equation is not balanced?

AC6H12O6 + 3O2 → 6CO2 + 6H2O
B2HCl + CaCO3 → CaCl2 + CO2 + H2O
C2KClO3 → 2KCl + 3O2
D4P + 5O2 → 2P2O5
Answer [1]

Source: 2023 XMS Sec 3 WA2 Q5

5

Mercury hydroxide reacts with phosphoric acid in the reaction below. w Hg(OH)2 + x H3PO4 → y Hg3(PO4)2 + z H2O. Which values of w, x, y and z correctly balance the equation?

wxyz
A2314
B3327
C3216
D64211
Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q23

6

Which compound contains the highest percentage of nitrogen by mass?

AAl(NO3)3
BMg3N2
CNO
DNO2
Answer [1]

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

7

A new element was discovered. The relative abundance of its isotopes is shown below. What is its relative atomic mass?

nucleon number of isotope636567
relative abundance / %68.5429.511.95
A33.33
B63.67
C63.71
D65.00
Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q26

8

What is the empirical formula of a compound consisting of 4.8 g of carbon and 0.8 g of hydrogen?

ACH
BCH2
CC2H3
DC4H8
Answer [1]

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

9

A sample of nitrogen of mass 5.00 g is completely converted into an oxide of nitrogen. The mass of the oxide formed is 19.30 g. What is the empirical formula of the oxide?

ANO
BNO2
CN2O3
DN2O5
Answer [1]

Source: SJI 2020 Year 3 End-of-Year P1 Q15

B

Structured questions

18 marks
10

Balance the following chemical equations.

(a)
…… S8 + …… O2 → …… SO3
[1]
(b)
…… C3H8 + …… O2 → …… CO2 + …… H2O
[1]
(c)
…… AlBr3 + …… K2SO4 → …… KBr + …… Al2(SO4)3
[1]

Source: 2023 XMS Sec 3 WA2 Q6

11

Write the chemical equations for the following reactions.

(a)
Sodium metal reacts with water to form hydrogen gas and sodium hydroxide.
[1]
(b)
Nitric acid reacts with calcium oxide to form calcium nitrate and water.
[1]
(c)
Propene (C3H6) burns in oxygen to form carbon dioxide and water.
[1]

Source: 2022 XMS Sec 3 WA2 B3(a)

12

A student prepares barium sulfate by mixing two solutions, barium nitrate and potassium sulfate. Barium sulfate is collected as the residue.

(a)
Write a balanced chemical equation for the reaction between barium nitrate and potassium sulfate.
[1]
(b)
Hence, construct the ionic equation for the reaction.
[1]

Source: SJI 2020 Year 3 End-of-Year P2 A5(a)

13

Carbon can be reacted with boron to form compound R. A sample of R was found to contain 78.6% boron by mass.

Deduce the empirical formula of R. Show your working.
[3]

Source: 2024 CHS Sec 3 End-of-Year Section B Q3(b)

14

25.0 cm3 of 0.40 mol/dm3 sulfuric acid was reacted with exactly 35 cm3 of sodium hydroxide. H2SO4 + 2NaOH → Na2SO4 + 2H2O

(a)
Calculate the concentration of sodium hydroxide used.
[2]
(b)
Write the ionic equation, with state symbols, for this reaction.
[1]

Source: 2023 GESS Sec 3 End-of-Year P2 B11(a) and (b)

15

Wollastonite, CaSiO3, can be produced from the reaction between calcium phosphate and silicon dioxide. 2Ca3(PO4)2 + 6SiO2 → P4O10 + 6CaSiO3. 100 g of calcium phosphate, Ca3(PO4)2, was used in this reaction. The actual mass of wollastonite produced was 87 g.

Calculate the percentage yield of wollastonite.
[4]

Source: 2023 GESS Sec 3 End-of-Year P2 A9