Group 2, the alkaline earth metalsAQA A-Level Chemistry: Topic test

20 questions, 54 marks

AQA A-Level Chemistry

Group 2, the alkaline earth metals topic test

Total 54 marks

Name

Class

Date

1
The atomic radii of the Group 2 elements increase down the group: magnesium 0.160 nm, calcium 0.197 nm, strontium 0.215 nm and barium 0.222 nm. Barium reacts rapidly with cold water.
(a)
Which statement explains why atomic radius increases down Group 2?
[1 mark]
AThe nuclear charge decreases down the group
BEach element has one more occupied electron shell than the one above it
CThe number of electrons in the outer shell increases down the group
DThe atoms lose electrons and become larger
(b)
Which statement best explains why the first ionisation energy decreases down Group 2?
[1 mark]
AThe nuclear charge decreases, so the outer electron is held less strongly
BThe atoms have fewer protons, so less energy is needed
CMore energy is needed because larger atoms have more electrons to remove
DThe outer electron is further from the nucleus and more shielded, which outweighs the increased nuclear charge
(c)
Write an equation, including state symbols, for the reaction of barium with cold water and state one observation that would be made.
[2 marks]
Total for question 1: 4 marks
2
A technician investigates the solubility of Group 2 compounds. She adds dilute sodium sulfate solution to separate dilute solutions of magnesium nitrate, calcium nitrate and barium nitrate. She also compares the pH of saturated solutions of the Group 2 hydroxides.
(a)
Which solution gives the most obvious white precipitate with sodium sulfate solution?
[1 mark]
AMagnesium nitrate
BCalcium nitrate
CBarium nitrate
DAll three give the same amount of precipitate
(b)
Which statement about the Group 2 hydroxides is correct?
[1 mark]
AThe solubility increases down the group, so a saturated solution of barium hydroxide is more alkaline than one of calcium hydroxide
BThe solubility decreases down the group, so a saturated solution of barium hydroxide is the least alkaline
CMagnesium hydroxide is more soluble than calcium hydroxide
DAll the Group 2 hydroxides are insoluble in water
(c)
Write an ionic equation, including state symbols, for the formation of the precipitate when sodium sulfate solution is added to barium nitrate solution. Explain why no precipitate forms with magnesium nitrate solution.
[2 marks]
Total for question 2: 4 marks
3
A student reacts 0.685 g of barium with excess cold water and makes the resulting solution up to 250 cm³ with distilled water. Use these relative atomic masses: Ba 137, S 32.1, O 16.0. The molar volume of a gas is 24.0 dm³ mol⁻¹ at room temperature and pressure.
(a)
Write an equation for the reaction of barium with water. Calculate the volume of hydrogen gas produced, in cm³.
[3 marks]
(b)
She then adds an excess of dilute sulfuric acid to the whole 250 cm³ of solution and collects, washes and dries the precipitate. Calculate the maximum mass of barium sulfate obtained.
[4 marks]
Total for question 3: 7 marks
4
A stream running through a disused mine is acidic because it contains dilute hydrochloric acid, and it also contains dissolved magnesium chloride and sodium sulfate. A water treatment works considers two treatments: adding calcium hydroxide (slaked lime), and adding barium chloride solution.
(a)
Explain how adding calcium hydroxide would change the stream, with reference to the acid and to the magnesium ions. Include equations. Ignore any effect on the sulfate ions.
[6 marks]
(b)
Evaluate the proposal to add barium chloride solution to remove the sulfate ions from the stream.
[6 marks]
Total for question 4: 12 marks
5
A student has two white solids, barium carbonate and barium sulfate, and adds each to dilute hydrochloric acid.
(a)
Which pair of aqueous solutions, when mixed, forms a white precipitate?
[1 mark]
ABarium chloride and magnesium sulfate
BMagnesium chloride and calcium nitrate
CCalcium chloride and sodium nitrate
DMagnesium nitrate and sodium chloride
(b)
Which statement explains why barium sulfate shows no change when dilute hydrochloric acid is added?
[1 mark]
ASulfate ions react with hydrogen ions to form sulfur dioxide
BBarium ions react with chloride ions to form insoluble barium chloride
CBarium sulfate is insoluble and sulfate ions do not react with the acid
DBarium sulfate reacts with the acid but the products are colourless
(c)
Write an equation, including state symbols, for the reaction of barium carbonate with dilute hydrochloric acid and explain why the solid disappears.
[2 marks]
Total for question 5: 4 marks
6
A student adds small pieces of strontium to cold water and tests the solution formed. Strontium is in Group 2, below calcium.
(a)
Which statement about this reaction is correct?
[1 mark]
AStrontium reacts less vigorously than calcium
BThe solution formed is acidic
CStrontium oxide is the only product
DThe solution formed is alkaline because it contains hydroxide ions
(b)
What amount of hydrogen, in mol, is produced when 0.020 mol of strontium reacts with excess water?
[1 mark]
A0.010
B0.020
C0.040
D0.0010
(c)
Explain, in terms of electron configuration, why strontium forms Sr²⁺ ions in its reactions.
[2 marks]
Total for question 6: 4 marks
7
Calcium and magnesium compounds have many uses. A factory removes sulfur dioxide from its flue gas using calcium oxide, and an indigestion tablet contains 0.500 g of magnesium hydroxide. Use these relative atomic masses: H 1.0, O 16.0, Mg 24.3.
(a)
Write an equation for the reaction of calcium oxide with sulfur dioxide and explain why removing sulfur dioxide from the flue gas is important.
[3 marks]
(b)
Stomach acid is hydrochloric acid of concentration 0.100 mol dm⁻³. Calculate the volume of this acid, in cm³, that the tablet can neutralise.
[4 marks]
Total for question 7: 7 marks
8
A student compares magnesium and barium. She notes that barium has a much larger atomic radius than magnesium, that barium reacts rapidly with cold water whereas magnesium reacts only very slowly, and that magnesium is used industrially to extract titanium from titanium(IV) chloride. She also has aqueous solutions of magnesium chloride and barium chloride in unlabelled bottles.
(a)
Explain why barium is more reactive towards water than magnesium, and describe the role of magnesium in the extraction of titanium, including an equation.
[6 marks]
(b)
Describe how adding sodium hydroxide solution and, separately, dilute sulfuric acid to samples of the two solutions would distinguish them. Explain the observations in terms of trends in solubility.
[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).