Making ammonia The Haber process

1. Making ammoniaThe Haber process

2. The Haber processWhat do we need? Where do we get the nitrogen and hydrogen? • Nitrogen – Fractional distillation of air • Hydrogen – From natural gas, CH4 (reforming). Also electrolysis of water.

3. Why is the Haber process so important? Plants need nitrogen to grow. They get this from soluble nitrates (NO3-) in the soil. When we harvest plants, the nitrogen is not returned to the soil. Ammonia is used to make nitrate fertilisers to replenish the soil.

4. The Haber processWhat are the conditions? • Iron catalyst • High temperature (450oC) • High pressure (200atm)

5. The Haber processIt’s reversible • There is always a mixture of nitrogen, hydrogen and ammonia. • How do we get the ammonia pure?

6. The Haber processIt’s reversible • Ammonia has a higher boiling point than hydrogen and nitrogen. • The reaction mixture is cooled and the ammonia condenses.

7. The Haber processIt’s reversible • The liquefied ammonia is collected. • The hydrogen and ammonia gases are recycled back into the reaction vessel.

8. Making ammoniaThe Haber process 450oC 200atm Iron catalyst

9. Ammonia is an important chemical used for making …………………… The raw materials to make it are …………………… (from the …………………) and …………………. (mainly from natural ………………….). Theses are reacted at about …………………oC and ………………….. atmospheres pressure using an ………………….. catalyst. Ammonia is removed from the reaction mixture by …………………. it. This ……………….. the ammonia gas. List three conditions for the Haber process 1. 2. 3. Write a word and symbol equation for the Haber process Word bank: air, fertilisers, gas, 450, hydrogen, iron, liquefies, nitrogen, 200, cooling Complete a flow chart of the Haber process in the boxes below Where do the reactants for the Haber process come from? Nitrogen – Hydrogen – Why is the Haber process so important? ………………………………………………………………………………… ................................................................................... …………………………………………………………………………………