Balanced equations and reacting massesEdexcel International A Level Chemistry: Subtopic test

1. 1
   A student places granules of zinc in blue copper(II) sulfate solution, CuSO₄(aq), and watches the reaction over several minutes.

   (a)

   Which is the correct ionic equation, with state symbols, for the reaction?

   [1 mark]

   • AZn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)
   • BZn²⁺(aq) + Cu(s) → Zn(s) + Cu²⁺(aq)
   • CZn(s) + Cu²⁺(aq) → Zn⁺(aq) + Cu(s)
   • DZn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)

   (b)

   Which observations would the student record?

   [1 mark]

   • AThe solution turns from colourless to blue
   • BA grey solid forms and the solution turns green
   • CThe blue colour fades and a brown (pink) solid forms
   • DA white precipitate forms and a gas is given off

   (c)

   Explain why this reaction occurs, and identify the spectator ion.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student adds magnesium carbonate in small portions to 50.0 cm³ of hydrochloric acid of concentration 1.00 mol dm⁻³ until no more solid dissolves. Relative atomic masses: C = 12.0, O = 16.0, Mg = 24.3.

   (a)

   Which observation would the student make?

   [1 mark]

   • AThe solid turns blue
   • BThe solid dissolves with effervescence
   • CA white precipitate forms
   • DThe solution turns pink

   (b)

   Which is the correct ionic equation, with state symbols, for the reaction?

   [1 mark]

   • AMgCO₃(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂O(l) + CO₂(g)
   • BCO₃²⁻(aq) + 2H⁺(aq) → H₂O(l) + CO₂(g)
   • CMgCO₃(s) + H⁺(aq) → Mg²⁺(aq) + H₂O(l) + CO₂(g)
   • DMgCO₃(s) + 2HCl(aq) → MgCl₂(aq) + H₂O(l) + CO₂(g)

   (c)

   Calculate the maximum mass of magnesium carbonate that can react with the acid.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A teacher demonstrates a precipitation reaction by mixing 25.0 cm³ of 0.100 mol dm⁻³ lead(II) nitrate solution, Pb(NO₃)₂(aq), with an excess of potassium iodide solution, KI(aq). Relative atomic masses: I = 126.9, Pb = 207.2.

   (a)

   Write the full equation, with state symbols, and the ionic equation, with state symbols, for the reaction, and state what is observed.

   [3 marks]

   (b)

   Calculate the mass of lead(II) iodide formed.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials chemist studies two reactions of aluminium. Part 1: the thermite reaction, in which aluminium reduces iron(III) oxide, Fe₂O₃, to iron and aluminium oxide, Al₂O₃. Part 2: 2.70 g of aluminium is added to 50.0 cm³ of hydrochloric acid of concentration 2.00 mol dm⁻³. Relative atomic masses: O = 16.0, Al = 27.0, Cl = 35.5, Fe = 55.8.

   (a)

   For Part 1, write a balanced equation with state symbols, then calculate the mass of aluminium needed to react completely with 80.0 g of iron(III) oxide and the mass of iron formed.

   [6 marks]

   (b)

   For Part 2, write the ionic equation with state symbols, identify the limiting reagent, and calculate the mass of aluminium chloride formed and the mass of aluminium left over.

   [6 marks]

   Total for question 4: 12 marks

End of questions