The Haber Process and the Industrial Compromise · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
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The factory that argues with equilibrium

Science · Matter & Materials · ages 15-16
Name ______________________   Date ____________

  1. What does the iron catalyst do in the Haber reactor?

    • It moves equilibrium toward more ammonia
    • It raises the yield beyond the limit
    • It gets to equilibrium faster at a practical speed

  2. Which conditions give the best yield of ammonia on paper?

    • High temperature and low pressure
    • Low temperature and high pressure
    • High temperature and high pressure

  3. In the Haber process, ammonia can split back into nitrogen and hydrogen.

    Circle one:   True   False

  4. Why do real plants run near 450 degrees instead of cold?

    • Cold would give a hopelessly slow rate, while heat buys speed worth more than the lost yield
    • Cold would destroy the iron catalyst
    • Heat pushes the yield higher than cold ever could

  5. The forward reaction gives out heat. What does cooling the mixture do?

    • It shifts the balance toward nitrogen and hydrogen
    • It changes the speed but not the balance
    • It shifts the balance toward more ammonia

  6. Nitrogen and hydrogen turn 4 gas molecules into 2 molecules of ammonia. If 12 molecules of the starting mixture react fully, how many ammonia molecules form?

    Answer: ______________

  7. What happens to the nitrogen and hydrogen that do not react in one pass?

    • Ammonia is condensed out and the leftover gases loop back round
    • They are burned off as waste gas
    • They are buried along with the catalyst

  8. A student says the catalyst raises the ammonia yield. What is wrong?

    • Catalysts only work in cold mixtures
    • It speeds both directions equally, so the final mixture is unchanged
    • Iron is used up, so it cannot change anything
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Answer key

For grown-ups. Fold this page away before handing over the rest.

The factory that argues with equilibrium W1-mt_J-JkijqnY5-s1

  1. It gets to equilibrium faster at a practical speed · The catalyst buys speed in both directions and never moves the final mixture.
  2. Low temperature and high pressure · Cold favours the heat giving step and pressure favours the side with fewer gas molecules.
  3. True · That back step is why the mixture settles at equilibrium instead of finishing.
  4. Cold would give a hopelessly slow rate, while heat buys speed worth more than the lost yield · Heat trades a little yield for a much faster rate, and recycling covers the loss.
  5. It shifts the balance toward more ammonia · Cooling an exothermic step makes more product to replace the lost heat.
  6. 6 · Four in gives two out, so twelve in gives six out.
  7. Ammonia is condensed out and the leftover gases loop back round · Condensing the product out and recycling the rest turns a modest pass into a paying process.
  8. It speeds both directions equally, so the final mixture is unchanged · Rate is the whole job of the catalyst, and yield is none of its business.
Worksheet · LightMySky