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AS · Practice questions · Group 2 metals and their reactions

Watch it fizz.

Six original Cambridge-style questions on the Group 2 metals: trends, equations, observations and a reacting-volume calculation.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
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Bigger atom, easier to ionise, more reactive.

01
Explain
[3 marks]

Explain why the first ionisation energy decreases from magnesium to barium.

  • The atoms have more electron shells, so the outer electron is further from the nucleus. ✓
  • There is more shielding by inner electrons. ✓
  • These outweigh the increase in nuclear charge, so less energy is needed to remove the outer electron. ✓
02
Recall
[3 marks]

Write equations for the reactions of (a) strontium with water, (b) magnesium with steam and (c) calcium with dilute hydrochloric acid.

  • (a) Sr + 2H2O → Sr(OH)2 + H2. ✓
  • (b) Mg + H2O(g) → MgO + H2. ✓
  • (c) Ca + 2HCl → CaCl2 + H2. ✓
03
Recall
[2 marks]

Describe what is seen when magnesium ribbon is burned in air, and write the equation.

  • A very bright white flame and a white powder (ash) is left. ✓
  • 2Mg + O2 → 2MgO. ✓
04
Calculation
[2 marks]

Calculate the volume of hydrogen at room conditions formed when 0.200 g of calcium reacts with excess water. (Ar Ca 40.1)

  • n(Ca) = 0.200 ÷ 40.1 = 4.99 × 10−3 mol = n(H2). ✓
  • V = 4.99 × 10−3 × 24.0 = 0.120 dm3 (120 cm3). ✓
05
Explain
[2 marks]

Barium oxide is added to water and the solution tested with universal indicator. Write the equation and predict the colour.

  • BaO + H2O → Ba(OH)2. ✓
  • Ba(OH)2 is quite soluble and strongly alkaline, so the indicator turns purple (pH about 13 to 14). ✓
06
Explain
[2 marks]

Explain why the reaction of calcium with dilute sulfuric acid slows down quickly, while its reaction with dilute hydrochloric acid continues.

  • Calcium sulfate is only sparingly soluble, so it forms a coating on the calcium that keeps the acid away. ✓
  • Calcium chloride is soluble, so the metal surface stays exposed. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.