Chapter 7 Practice Paper: Salts and Qualitative Analysis — question paper

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

1. 1

   Which pair consists of two salts that are both insoluble in water?

   1. Asodium sulfate and ammonium nitrate
   2. Bbarium sulfate and lead(II) chloride
   3. Cpotassium carbonate and calcium carbonate
   4. Dsilver chloride and sodium chloride
   ( )
2. 2

   A colourless gas relights a glowing splint. The gas is

   1. Ahydrogen
   2. Bcarbon dioxide
   3. Coxygen
   4. Dchlorine
   ( )
3. 3

   Excess solid magnesium oxide is stirred into dilute sulfuric acid when making magnesium sulfate crystals. The solid is added in excess because this

   1. Aguarantees that all of the acid reacts
   2. Bmakes the fizzing reaction faster
   3. Chelps the magnesium oxide dissolve completely
   4. Dkeeps the mixture warm overnight
   ( )
4. 4

   A student wants golden-yellow crystals of lead(II) iodide. Which route gives a pure, dry sample?

   1. Aadding excess lead(II) carbonate to dilute hydrochloric acid
   2. Btitrating lead(II) nitrate solution against potassium iodide solution with an indicator
   3. Cheating lead(II) carbonate strongly in a test-tube
   4. Dmixing lead(II) nitrate solution with potassium iodide solution, then filtering, washing and drying the solid
   ( )
5. 5

   Which observation confirms ammonium ions in a solution?

   1. Aaqueous sodium hydroxide gives a white precipitate
   2. Bdilute hydrochloric acid gives brisk effervescence
   3. Con warming with aqueous sodium hydroxide, a pungent gas turns damp red litmus blue
   4. Dacidified silver nitrate gives a white precipitate
   ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. Include state symbols where the question asks, and balance every equation.

1. 1

   A class makes zinc sulfate crystals by reacting dilute sulfuric acid with zinc oxide.

   1. (a)

      Name the two reagents and write the equation for the reaction.

      [2]
   2. (b)

      Explain why the zinc oxide is added in excess and the mixture is then filtered before evaporation.

      [2]
   3. (c)

      Describe how crystals of zinc sulfate are obtained from the filtrate.

      [2]
2. 2

   7.15 g of hydrated sodium carbonate crystals, Na₂CO₃·xH₂O, are heated to constant mass. The anhydrous sodium carbonate remaining weighs 2.65 g. (Mr: Na₂CO₃ = 106, H₂O = 18.)

   1. (a)

      Calculate the moles of anhydrous sodium carbonate.

      [2]
   2. (b)

      Work out the amount, in mol, of water lost on heating.

      [1]
   3. (c)

      Deduce the value of x.

      [2]
3. 3

   Two colourless solutions, P and Q, each give a white precipitate with aqueous sodium hydroxide that dissolves in excess. With aqueous ammonia, the precipitate from P stays but the one from Q dissolves.

   1. (a)

      Identify the cation in each solution (P and Q).

      [2]
   2. (b)

      Show, with an ionic equation including state symbols, how the precipitate from Q forms from the ions in its solution.

      [2]
   3. (c)

      Name the compound in the precipitate from Q.

      [1]
4. 4

   A colourless, sharp-smelling gas G is produced when sulfur burns in air. G turns acidified potassium manganate(VII) from purple to colourless.

   1. (a)

      Name gas G.

      [1]
   2. (b)

      Write the equation for the burning of sulfur in air.

      [1]
   3. (c)

      Name one other gas that bleaches damp litmus paper.

      [1]
   4. (d)

      Explain why damp blue litmus turns red in gas G.

      [1]