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Equilibrium &The Haber Process GCSE REVISION. The Haber Process  This reaction makes ammonia out of hydrogen and nitrogen.  The nitrogen comes from.

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Presentation on theme: "Equilibrium &The Haber Process GCSE REVISION. The Haber Process  This reaction makes ammonia out of hydrogen and nitrogen.  The nitrogen comes from."— Presentation transcript:

1 Equilibrium &The Haber Process GCSE REVISION

2 The Haber Process  This reaction makes ammonia out of hydrogen and nitrogen.  The nitrogen comes from the air (78% N).  You don’t need to worry about where the hydrogen comes from!

3 1. What does Reversible Reaction mean ? A reaction that can proceed in both directions

4 The Haber Process  The Haber process is a REVERSIBLE reaction N 2(g) + 3H 2(g) 2NH 3(g) (+ heat) nitrogen + hydrogen ammonia A reversible reaction is one where the products of the reaction can themselves react to produce the original reactants.

5 2. a. What does the Haber Process make? b. Give one use of this product  Ammonia  To make fertilisers

6 3. There are Three Raw Materials for the Haber Process. What are they?  Nitrogen is easily obtained from air by fractional distillation  Hydrogen is obtained from methane reacted with steam.  methane + steam carbon dioxide + hydrogen. CH 4 (g) + 2H 2 O(g) CO 2 (g) + 4H 2 (g)  The raw materials are therefore air - for nitrogen, methane and water - for hydrogen.

7 4. Write the word/balanced chemical equation for the Haber Process.  nitrogen + hydrogen ammonia ( + heat)  N 2 (g) + 3H 2 (g) 2NH 3 (g) ( + heat)

8 The Haber Process

9 The Haber Key facts 1. H and N are mixed in a 3:1 ratio 2. Because the reaction is reversable not all the nitrogen and hydrogen will convert to ammonia. 3. The ammonia forms as a gas but cools and liquefies in the condenser 4. The H and N which do not react are passed through the system again so they are not wasted.

10 5. In a Reversible Reaction, how can the Yield be Changed?  Change the conditions (use of temperature, pressure and catalyst).  This is a useful summary for any reversible reaction including the Haber Process. Haber ProcessHaber Process  1. Increasing the temperature favours the endothermic reaction. Increasing the temperatureIncreasing the temperature  2. Increasing the pressure favours the smaller volume. Increasing the pressureIncreasing the pressure  3. Using a catalyst gives the equilibrium conditions more quickly. Using a catalystUsing a catalyst

11 6. Why is the Haber Process run at 450 °C instead of room temperature?  To increase rate of reaction

12 7. Why is the Haber Process run at High Pressure? Give two reasons.  Increasing the pressure (from Le Chatelier's Principle) makes the equilibrium mixture have more ammonia. Le Chatelier's PrincipleLe Chatelier's Principle  Increased pressure also increases the reaction rate. ncreased pressurencreased pressure

13 8. Why is the Haber Process not run at Very High Pressure?  Too expensive

14 9. Which Substance is used as a Catalyst in the Haber Process?  Iron catalyst

15 The following questions are Higher Tier only

16 10. Use Le Chatelier's Principle to explain what happens as a Product is removed  If you remove a product, the equilibrium mixture changes to make more product. equilibrium mixtureequilibrium mixture  It tries to get back to the composition it had before the product was removed.  You can carry on removing product until all the reactants have turned into product

17 11. Use Le Chatelier's Principle to explain what happens as Heat is Removed.  Heat may be treated as a reactant (for an endothermic reaction) or as a product (for an exothermic reaction). endothermic exothermic endothermic exothermic  If you remove heat from an exothermic reaction the equilibrium will change to produce more product.  If you add heat to an exothermic reaction (raise its temperature),the reverse will happen, and you will get less product in the equilibrium mixture.

18 12. What effect does a Catalyst have on the Equilibrium Composition?  No effect.  Equilibrium is just reached more quickly.


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