Chapter 13 Practice Paper: Reversible reactions, equilibrium and industry — question paper

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

1. 1

   At equilibrium the rate of the forward reaction is

   1. Azero
   2. Bequal to the rate of the reverse reaction
   3. Cgreater than the reverse rate
   4. Dsteadily increasing
   ( )
2. 2

   Increasing the pressure on N₂(g) + 3H₂(g) ⇌ 2NH₃(g)

   1. Ashifts the equilibrium to the left
   2. Bhas no effect on the position
   3. Cshifts the equilibrium to the right, making more ammonia
   4. Dslows the reaction down
   ( )
3. 3

   Adding a catalyst to an equilibrium mixture changes

   1. Athe position of equilibrium
   2. Bthe equilibrium yield
   3. Cthe temperature the system settles at
   4. Donly the rate at which equilibrium is reached
   ( )
4. 4

   The forward reaction is exothermic. Raising the temperature shifts the equilibrium

   1. Ato the left, in the endothermic direction
   2. Bto the right, in the exothermic direction
   3. Ctowards the catalyst
   4. Dnot at all
   ( )
5. 5

   A run collects 12 g of product where 60 g was theoretically possible. The percentage yield is

   1. A72%
   2. B20%
   3. C5%
   4. D50%
   ( )
6. 6

   A reaction is guaranteed an atom economy of 100% when

   1. Athe yield happens to be high
   2. Ba catalyst is used
   3. Conly one product is formed
   4. Dthe reactants are cheap
   ( )
7. 7

   The catalyst used in the Haber process is

   1. Aplatinum
   2. Bnickel
   3. Cvanadium pentoxide
   4. Diron
   ( )
8. 8

   The Haber process is not run at a much lower temperature because

   1. Athe rate would be far too slow
   2. Bammonia would not condense
   3. Cthe catalyst would melt
   4. Dhydrogen would become a solid
   ( )
9. 9

   Ammonia is removed from the Haber recycle loop by

   1. Afiltering
   2. Bcooling it until it condenses
   3. Celectrolysis
   4. Dneutralising it with acid
   ( )
10. 10

    The main plant nutrient supplied by ammonium nitrate is

    1. Aphosphorus
    2. Bpotassium
    3. Cnitrogen
    4. Dsulfur
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

1. 11

   This question is about hydrated copper(II) sulfate: hydrated CuSO₄ ⇌ anhydrous CuSO₄ + water.

   1. (a)

      State the colours of the hydrated and anhydrous salts.

      [2]
   2. (b)

      State why the mixture in a sealed tube can reach dynamic equilibrium.

      [1]
   3. (c)

      Describe what is meant by dynamic equilibrium in this tube.

      [2]
2. 12

   This question is about the Haber process: N₂(g) + 3H₂(g) ⇌ 2NH₃(g), forward reaction exothermic.

   1. (a)

      State the temperature, pressure and catalyst used.

      [3]
   2. (b)

      Explain why the temperature is a compromise.

      [3]
   3. (c)

      Explain why increasing the pressure increases the equilibrium yield, and why 200 atm is chosen rather than 1000 atm.

      [3]
3. 13

   A cement works decomposes calcium carbonate: CaCO₃(s) → CaO(s) + CO₂(g). (Mr: CaCO₃ = 100, CaO = 56, CO₂ = 44)

   1. (a)

      Work out what percentage of the product mass is the desired calcium oxide.

      [2]
   2. (b)

      100 g of calcium carbonate theoretically makes 56 g of CaO; a kiln run makes 42 g. Calculate the percentage yield.

      [2]
   3. (c)

      Explain the difference between the atom economy and the percentage yield of this process.

      [2]