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Ammonia & Fertilizers. http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/chemreac/energychangesrev3.shtml. Today’s Lesson. Making Ammonia Pro’s & Con’s of Fertilizers Experiment. Making Ammonia.
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Ammonia & Fertilizers http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/chemreac/energychangesrev3.shtml
Today’s Lesson • Making Ammonia • Pro’s & Con’s of Fertilizers • Experiment
Making Ammonia • Making ammonia in industry is a big business. This is mainly completed through the Haber process. • Below is the basic process: • Raw materials of H & N mixed and scrubbed (cleaned) to get rid of any impurities • The gas is compressed into a smaller tank so that it is approximately 200 atmospheres (gas is 200 times closer than earth’s atmosphere)
Haber Process • 3. The gas goes through a converter which is made up of hot iron (450 C) that catalyzes or speeds up the reaction • N2 (g) + 3H2 (g) 2NH3 (g) • 4. The gas is cooled until Ammonia condenses into a liquid. The N & H is recycled using step 3 and 4. • 5. The ammonia is stored in tanks as a liquid under pressure until used.
Making A Profit • The yield and amount of pressure required to get different concentrations of Ammonia is important. • In general, a lower temperature and a higher pressure will produce more ammonia. • However, it’s all a game of economics. If it’s cheaper and faster to make it in lower concentrations and at a different temperature, industry will do this. • Remember that a lower temperature also means a slower reaction!!
Pro’s & Con’s of Fertilizers • Fertilizers have had positive and negative impacts on the earth as a whole. • They started off the Green Revolution in the 1960’s where many third world countries had access to fertilizers and were able to dramatically increase food production as a result. • Fertilizers can triple or even quadruple food production when used correctly. They have saved millions if not billions of lives.
Problems • Eutrophication – Plants love Nitrogen, it helps them grow faster. This is the same for water plants. If there is too much Nitrogen in still waterways, plants cover the surface of the water and stop Oxygen getting into the water. Fish and other animals die as a result • Nitrates that we eat are converted into Nitrites in the stomach. Put together with hemoglobin, they limit the amount of Oxygen that your blood can carry.
Finding The Middle Ground • There are many things humans can do to limit the use of Fertilizers. These include: • Using them sparingly • Removing Nitrates at water treatment plants • Limiting the use of fertilizers near running water to limit runoff (including keeping the banks of rivers treed) • Organic Farming??? • Leaving field vacant so they can increase in N naturally.
Questions • Read the following pages and answer the questions: • Making Ammonia in Industry Page 158-159 (Questions 1-3)The Pros and Cons of Fertilizers Page 162-162 (Questions 1-6)