Properties of Period 3 elements and their oxidesAQA A-Level Chemistry: Topic test

20 questions, 54 marks

AQA A-Level Chemistry

Properties of Period 3 elements and their oxides topic test

Total 54 marks

Name

Class

Date

1
Sodium and phosphorus are each heated and lowered into a gas jar of excess oxygen. Sodium burns with an intense yellow flame, leaving a white solid. Phosphorus burns with a bright white flame, producing white smoke.
(a)
What is the formula of the white smoke formed when phosphorus burns in excess oxygen?
[1 mark]
APO₅
BP₄O₆
CP₄O₁₀
DP₂O
(b)
Which equation correctly represents the combustion of sodium to form the white solid?
[1 mark]
A4Na + O₂ → 2Na₂O
BNa + O₂ → Na₂O
C2Na + O₂ → 2NaO
D4Na + 2O₂ → 2Na₂O
(c)
Sodium also reacts with cold water. Write an equation for this reaction and state the approximate pH of the solution formed.
[2 marks]
Total for question 1: 4 marks
2
Magnesium oxide is used to line furnaces and has a melting point of 3125 K. Silicon dioxide, the main component of sand, melts at 1986 K. Sulfur trioxide melts at 290 K.
(a)
Which statement best explains why magnesium oxide has a much higher melting point than sulfur trioxide?
[1 mark]
AMagnesium oxide contains covalent bonds that are stronger than those in sulfur trioxide
BMuch more energy is needed to overcome the strong electrostatic attraction between ions in magnesium oxide than the weak forces between sulfur trioxide molecules
CSulfur trioxide has stronger London forces between its molecules than magnesium oxide has between its ions
DMagnesium oxide is a giant covalent structure
(b)
Which statement about silicon dioxide is correct?
[1 mark]
AIt consists of simple SiO₂ molecules with Si=O double bonds
BIt is an ionic lattice of Si⁴⁺ and O²⁻ ions
CIt is held together by metallic bonding
DIt is a giant covalent structure in which each silicon atom is bonded to four oxygen atoms
(c)
Phosphorus(V) oxide, P₄O₁₀, has a much higher melting point than sulfur trioxide, SO₃. Explain why.
[2 marks]
Total for question 2: 4 marks
3
A technician dissolves 2.84 g of phosphorus(V) oxide, P₄O₁₀, in an excess of water and makes the solution up to 250 cm³. Relative atomic masses: P 31.0, O 16.0.
(a)
Write an equation for the reaction of phosphorus(V) oxide with water and calculate the concentration of the acid formed, in mol dm⁻³.
[3 marks]
(b)
A 25.0 cm³ sample of this solution is neutralised completely by sodium hydroxide solution of concentration 0.200 mol dm⁻³ to form sodium phosphate, Na₃PO₄. Write an equation and calculate the volume of sodium hydroxide solution needed, in cm³.
[4 marks]
Total for question 3: 7 marks
4
A chemist is studying Period 3 oxides. In one experiment, solid aluminium oxide is shaken separately with dilute hydrochloric acid and with hot concentrated sodium hydroxide solution, and it dissolves in both. In another, she considers the sulfur impurity in coal, which burns in oxygen when the coal is burned in a boiler.
(a)
Explain the behaviour of aluminium oxide, with equations, and state what would be seen if magnesium oxide and silicon dioxide were each treated in the same way. State how the acid-base character of the oxides changes across the period.
[6 marks]
(b)
Explain how sulfur dioxide forms when the coal burns and why it makes rainwater acidic, including equations. Explain also how sulfur trioxide would differ from sulfur dioxide in its effect on the water, and how sodium hydroxide solution could be used to remove sulfur dioxide from the flue gas. Give the formula of the anion present in each of the two acids.
[6 marks]
Total for question 4: 12 marks
5
Aluminium is a reactive metal, yet aluminium saucepans are unaffected by air and water. When aluminium powder is sprinkled into a flame it burns with a bright white flame.
(a)
Why do aluminium saucepans not react with water?
[1 mark]
AAluminium is below hydrogen in the periodic table
BAluminium does not lose electrons
CAluminium oxide is soluble in water
DA thin layer of unreactive aluminium oxide protects the metal
(b)
What is the formula of the oxide formed when aluminium powder burns?
[1 mark]
AAlO
BAl₂O₃
CAl₃O₂
DAlO₃
(c)
Write an equation for the combustion of aluminium in oxygen and explain why aluminium powder burns in a flame whereas a piece of aluminium foil does not.
[2 marks]
Total for question 5: 4 marks
6
Sulfur dioxide is used as a preservative in dried fruit. It dissolves in water to form an acidic solution.
(a)
Which row gives the acid formed when sulfur dioxide reacts with water and the anion it contains?
[1 mark]
AH₂SO₃ and SO₃²⁻
BH₂SO₄ and SO₄²⁻
CH₂S and S²⁻
DH₂SO₃ and SO₄²⁻
(b)
Which oxide gives a solution with a pH closest to 14 when added to water?
[1 mark]
ASO₃
BMgO
CNa₂O
DSiO₂
(c)
Write an equation for the reaction of sulfur dioxide with an excess of sodium hydroxide solution and name the salt formed.
[2 marks]
Total for question 6: 4 marks
7
A student burns 0.486 g of magnesium ribbon in excess oxygen and adds all the white solid formed to 100 cm³ of water. A second student adds the same amount, in moles, of sodium oxide to another 100 cm³ of water. Relative atomic masses: Mg 24.3, O 16.0.
(a)
Write an equation for the combustion of magnesium and calculate the mass of white solid formed.
[3 marks]
(b)
The solution from magnesium oxide has a pH of about 10, whereas that from sodium oxide has a pH of about 14. Write equations for both reactions with water and explain the difference in pH.
[4 marks]
Total for question 7: 7 marks
8
Three Period 3 elements are described. Element X reacts vigorously with cold water to form a strongly alkaline solution and burns in oxygen with an intense yellow flame. Element Y is a yellow solid that burns in oxygen with a blue flame to give a gas that dissolves in water to form an acidic solution. Element Z is a white solid that burns in oxygen with a bright white flame to give a white solid that reacts with water to form a strongly acidic solution. The melting points of the highest oxides of magnesium, silicon, phosphorus and sulfur are approximately: MgO 3125 K, SiO₂ 1986 K, P₄O₁₀ 613 K and SO₃ 290 K.
(a)
Identify X, Y and Z. Write equations for the reactions of the oxides of X and Z with water and explain the difference between the pH values of the two solutions in terms of bonding.
[6 marks]
(b)
A student states: 'Silicon dioxide has the highest melting point of the Period 3 oxides because giant covalent structures always have higher melting points than ionic ones.' Evaluate this statement using the melting points given.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).