Group 2 Exam Questions and Answers 2023 Graded A
Use the Periodic Table to deduce the full electron configuration of calcium.
1s2 2s2 2p6 3s2 3p6 4s2
Write an ionic equation, with state symbols, to show the reaction of calcium with an excess of water.
Ca(s)+ 2H2O(l) → Ca2+(aq) + 2OH-(aq) + ...
Group 2 Exam Questions and Answers 2023 Graded A
Use the Periodic Table to deduce the full electron configuration of calcium.
1s2 2s2 2p6 3s2 3p6 4s2
Write an ionic equation, with state symbols, to show the reaction of calcium with
an excess of water.
Ca(s)+ 2H2O(l) → Ca2+(aq) + 2OH-(aq) + H2(g)
State the role of water in the reaction with calcium.
Oxidising agent
Write an equation to show the process that occurs when the first ionisation
energy of calcium is measured.
Ca(g) → Ca+(g) + e-
State and explain the trend in the first ionisation energies of the elements in
Group 2 from magnesium to barium.
Decrease
Ions get bigger / more (energy) shells
Weaker attraction of ion to lost electron
Calcium hydroxide is slightly soluble in water at room temperature. As the
temperature rises, the solubility decreases. When the maximum amount of solid
has dissolved at a particular temperature the solution is said to be saturated.
In an experiment, the solubility of calcium hydroxide was measured over a range
of temperatures. The results are shown in the graph.
Use data from the graph to calculate the concentration, in mol dm−3, of a
saturated solution of calcium hydroxide at 30 °C. Give your answer to 3
significant figures.
Show your working.
0.155 g per 100 cm3
(0..1) × 10 = 0.0209 mol dm−3
You are given a sample of saturated calcium hydroxide solution. Outline the
practical steps that you would take to determine the solubility of calcium
hydroxide in
this solution.
Take a known volume of the saturated solution
Evaporate the filtrate to dryness
Weigh the residue of known concentration
Zinc is similar to Group 2 metals and forms compounds containing Zn2+ ions.
Write an equation for the thermal decomposition of zinc carbonate to zinc oxide.
Calculate the percentage atom economy for the formation of zinc oxide from zinc
carbonate in this reaction.
ZnCO3 → ZnO + CO2
Percentage atom economy =
81..4
x 100
= 64.9
A laboratory technician discovered four badly−labelled bottles, each containing
one pure white solid. Each bottle contained a compound of a different Group 2
, metal (magnesium, calcium, strontium and barium).
Some tests were carried out on the solids or, if the compound was soluble, on the
aqueous solution. The results are given in the table.
One of the bottles has a very faint label that could be read as 'Magnesium
Sulfate'.
Use the information in the table to deduce which one of the four compounds is
magnesium sulfate and explain your answer.
Compound 1
No visible change with H2SO4
Gives white precipitate with NaOH
The bottle containing Compound 2 has a 'TOXIC' hazard symbol.
Use the information in the table to identify Compound 2.
Explain both observations in the reaction with H2SO4(aq).
BaCO3
The carbonate ion releases CO2 but the BaSO4 formed is highly insoluble.
Identify the compound that is strontium hydroxide.
Give an equation for the reaction of strontium hydroxide with sulfuric acid.
Compound 4
Sr(OH)2 + H2SO4 → SrSO4 + 2H2O
The elements in Group 2 from Mg to Ba can be used to show the trends in
properties down a group in the Periodic Table.
State the trend in atomic radius for atoms of the elements down Group 2 from Mg
to Ba
Give a reason for this trend.
Increases / gets bigger
More shells or sub-shells or (main) levels or sub-levels or orbitals (of
electrons)
The Group 2 elements react with water.
State the trend in reactivity with water of the elements down Group 2 from Mg to
Ba
Increases / gets more reactive / reacts more vigorously / violently (down the Group)
Write an equation for the reaction of strontium with water.
Sr + 2H2O → Sr(OH)2 + H2
Give the formula of the hydroxide of the element in Group 2 from Mg to Ba that is
most soluble in water.
Ba(OH)2
The table below shows observations of changes from some test-tube reactions of
aqueous solutions of compounds Q, R and S with five different aqueous
reagents. The initial colours of the solutions are not given.
Identify each of compounds Q, R and S.
Q is calcium or magnesium bromide
R is aluminium chloride
S is iron(III) sulfate
Write ionic equations for each of the positive observations with S.
Ba2+ + SO42- → BaSO4
[Fe(H2O)6]3+ + 3OH- → Fe(H2O)3(OH)3 + 3H2O
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