Chemical Industry and Energy ResourcesIB MYP Chemistry: Topic test

1. 1
   At an ammonia plant in Trinidad and Tobago, nitrogen from the air is reacted with hydrogen made from natural gas. The gas mixture that leaves the reactor contains ammonia, but also nitrogen and hydrogen that have not reacted. The mixture is cooled, the ammonia condenses as a liquid and is removed, and the remaining gases are sent back to the reactor.

   (a)

   Which equation represents the reaction in the Haber process?

   [1 mark]

   • AN₂ + 3H₂ ⇌ 2NH₃
   • BN₂ + H₂ ⇌ NH₃
   • CN₂ + 2H₂ ⇌ 2NH₃
   • D2N₂ + 3H₂ ⇌ 2NH₃

   (b)

   Which substance is used as the catalyst in the Haber process?

   [1 mark]

   • APlatinum
   • BVanadium(V) oxide
   • CIron
   • DCopper

   (c)

   Explain why the unreacted nitrogen and hydrogen are sent back to the reactor.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An energy company in Norway publishes a leaflet comparing fuels. It gives the energy released when 1 gram of each fuel burns completely: hydrogen 142 kJ, methane 55 kJ, petrol 46 kJ and ethanol 30 kJ.

   (a)

   Which fuel in the leaflet releases the most energy per gram?

   [1 mark]

   • AMethane
   • BHydrogen
   • CPetrol
   • DEthanol

   (b)

   Which fuel in the leaflet is a biofuel?

   [1 mark]

   • AMethane, the main gas in natural gas
   • BHydrogen
   • CPetrol
   • DEthanol

   (c)

   A laboratory burner burns 250 g of methane completely. Calculate the energy released, in kJ.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   An engineer at a new ammonia plant in Egypt must choose the operating conditions for the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), which uses an iron catalyst and gives out heat. She is given the percentage of ammonia in the equilibrium mixture. At 200 atmospheres: 39% at 400 °C, 27% at 450 °C and 18% at 500 °C. At 450 °C: 16% at 100 atmospheres, 27% at 200 atmospheres and 41% at 400 atmospheres.

   (a)

   Describe the effect on the percentage of ammonia of increasing the temperature and of increasing the pressure.

   [3 marks]

   (b)

   The plant actually runs at 450 °C and 200 atmospheres. Explain why these conditions are a compromise rather than the conditions that give the highest percentage of ammonia.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A copper mining company on the Copperbelt in Zambia uses sulfuric acid to dissolve copper from crushed ore. It buys acid made far away and brought in by road at high cost. The company is considering building its own Contact process plant beside the mine, using sulfur brought in by rail. The plant would employ local people. If it leaked, it could release sulfur dioxide, a toxic gas that causes acid rain, and large amounts of concentrated sulfuric acid would be stored on site.

   (a)

   Describe the main stages of the Contact process and explain why a temperature of about 450 °C is a compromise.

   [6 marks]

   (b)

   Discuss the advantages and disadvantages of building the sulfuric acid plant and decide whether the company should build it.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   Fiji is a small island nation in the Pacific. Most of its electricity comes from diesel generators that burn imported fuel. The government wants to add solar panels, wind turbines and biodiesel made from coconut oil.

   (a)

   Which energy resource is renewable?

   [1 mark]

   • AWind
   • BCoal
   • CNatural gas
   • DUranium

   (b)

   Which statement about biodiesel made from coconut oil is correct?

   [1 mark]

   • AIt is made from crude oil
   • BIt is renewable because coconut palms can be regrown
   • CIt releases no carbon dioxide when it burns
   • DIt is a fossil fuel

   (c)

   Explain why using biodiesel from coconut oil adds less carbon dioxide to the atmosphere overall than using diesel from crude oil.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   The Barakah nuclear power station in the United Arab Emirates generates electricity using uranium fuel. It releases no carbon dioxide while it generates electricity, but it produces radioactive waste that must be stored safely for thousands of years.

   (a)

   Which statement about uranium fuel is correct?

   [1 mark]

   • ABurning it releases large amounts of carbon dioxide
   • BIt is renewable because it is not burned
   • CIt is a finite resource that cannot be replaced once used
   • DIt is a fossil fuel formed from ancient plants

   (b)

   Which is a disadvantage of nuclear power compared with a coal-fired power station?

   [1 mark]

   • AIt releases more sulfur dioxide
   • BIt releases less energy per gram of fuel
   • CIt releases more carbon dioxide while generating electricity
   • DIts used fuel is radioactive waste that must be stored safely for a very long time

   (c)

   State two advantages of nuclear power compared with a coal-fired power station.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A student in Chennai wants to test the claim that a briquette made from compressed coconut shell releases more energy per gram than charcoal. She burns 1.0 g of each fuel in turn under a metal can holding 100 cm³ of water (100 g) and measures the temperature rise of the water.

   (a)

   Identify the independent variable, the dependent variable and one control variable in this investigation.

   [3 marks]

   (b)

   The charcoal raises the temperature of the water by 18 °C. Calculate the energy transferred to the water using energy (J) = mass of water (g) × 4.18 × temperature rise (°C). Explain why the energy released by the charcoal is greater than your answer, and suggest one improvement to the method.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A fertiliser company in Chile plans a new ammonia plant to supply farmers in Chile and neighbouring countries. Ammonia is made in the Haber process from nitrogen and hydrogen. The company can make the hydrogen from natural gas, which costs 2 US dollars per kilogram of hydrogen and releases about 10 kg of carbon dioxide for every kilogram of hydrogen made. Or it can make the hydrogen by electrolysis of water using electricity from a solar farm in the Atacama Desert, which costs 5 US dollars per kilogram of hydrogen and releases almost no carbon dioxide while it runs.

   (a)

   Use the information to evaluate which method of making hydrogen the company should choose.

   [6 marks]

   (b)

   Discuss the advantages and disadvantages of using nitrogen fertilisers made from Haber process ammonia, and reach a justified conclusion.

   [6 marks]

   Total for question 8: 12 marks

End of questions