Group 1 and 2 trends and reactionsEdexcel International A Level Chemistry: Subtopic test

1. 1
   The first ionisation energies of the Group 2 elements, in kJ mol⁻¹, are: beryllium 900, magnesium 738, calcium 590 and strontium 550. A student is using the data to study how ionisation energy changes down the group.

   (a)

   Which equation represents the first ionisation energy of calcium?

   [1 mark]

   • ACa(s) → Ca⁺(g) + e⁻
   • BCa(g) → Ca²⁺(g) + 2e⁻
   • CCa⁺(g) → Ca²⁺(g) + e⁻
   • DCa(g) → Ca⁺(g) + e⁻

   (b)

   Which value is the most likely first ionisation energy of barium, in kJ mol⁻¹?

   [1 mark]

   • A620
   • B560
   • C503
   • D780

   (c)

   Explain why the first ionisation energy decreases down Group 2.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hospital pharmacy stocks milk of magnesia (a suspension of magnesium hydroxide) as an antacid, and barium sulfate suspension for X-ray examinations of the gut. Soluble barium compounds are toxic.

   (a)

   Which Group 2 hydroxide gives the most alkaline saturated aqueous solution at room temperature?

   [1 mark]

   • ABarium hydroxide
   • BCalcium hydroxide
   • CMagnesium hydroxide
   • DStrontium hydroxide

   (b)

   Equal volumes of 0.1 mol dm⁻³ solutions of four Group 2 nitrates are each mixed with an equal volume of dilute sulfuric acid. Which nitrate gives no visible precipitate?

   [1 mark]

   • ACalcium nitrate
   • BMagnesium nitrate
   • CStrontium nitrate
   • DBarium nitrate

   (c)

   Explain why barium sulfate is safe to swallow for an X-ray examination, even though soluble barium compounds are toxic.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A fish farm manager finds that a pond has become acidic, with a hydrogen ion concentration of 1.0 × 10⁻³ mol dm⁻³ (pH 3.0). The pond holds 500 dm³ of water. She plans to add solid calcium oxide to neutralise the acid.

   (a)

   Explain, with an ionic equation, why adding calcium oxide to the pond raises its pH.

   [3 marks]

   (b)

   Calculate the minimum mass of calcium oxide needed to neutralise all the hydrogen ions in the pond. Give your answer to three significant figures.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A teacher demonstrates the reactions of freshly cut lithium and potassium with water, and of magnesium ribbon and barium with oxygen and with water, using small samples in a fume cupboard.

   (a)

   Compare the reactions of lithium and potassium with water, and explain the difference in their reactivity.

   [6 marks]

   (b)

   Describe the reactions of magnesium with oxygen and of barium with cold water, and explain why barium is more reactive than magnesium.

   [6 marks]

   Total for question 4: 12 marks

End of questions