Chemical Monitoring and Management

1. Chemical Monitoring and Management Year 12 Chemistry

2. Much of the work of chemists involves monitoring the reactants and products of reactions and managing reaction conditions 9.4.1

3. The role of the Chemist A variety of industries employ chemists. Some of these include: • Inorganic chemical synthesis • Organic chemical synthesis • Petrochemical industry • Pharmaceutical industry • Plastics industry • Mining industry • Food processing • Environmental analysis Chemists work with a variety of other professionals including plant managers, engineers, computer programmers and plant operators. It is essential that chemists are able to communicate with a variety of people from a different academic backgrounds

4. Inorganic Synthesis Chemist Chemists in this role assist in the production of chemicals such as: • Ammonia • Fertilisers • Explosives • Various acids Source: www.careers-scotland.org.uk These chemists are concerned with quality control of final products and may be involved in the development of new products.

5. Organic Synthesis Chemist Chemists in this role assist in the production of chemicals such as: • solvents • detergents • dyes • pesticides • herbicides Source: www.raci.org.au These chemists are concerned with quality control of final products and may be involved in the development of new products.

6. Petrochemical Chemist Chemists in this role are involved in the production of: • Petrol • Kerosene • Natural gas • LPG • Oils Source: www.kingsu.net These chemists are concerned with maximum yield, quality control of final products and may be involved in the development of new products.

7. Mining industry Chemists in this role do a variety of tasks including: • Environmental reclamation • Purification of minerals • Extraction of metals • Research • Analytical testing Source: www.ela-iet.com

8. Environmental chemist Chemists in these roles perform a variety of duties to monitor and protect the natural environment. Some roles include: • Monitoring water supplies • Monitoring air quality • Monitoring soil contamination • Analysing effluent from industry Chemists in this role use a variety of analytical techniques including wet chemical and modern instrumental analysis to monitor chemical contamination in the environment Source: www.careercornerstone.org

9. Combustion needs monitoring The products from the combustion of petrol depend upon the conditions of the reaction Complete combustion (plenty of O2) 2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O (l) Incomplete combustion (insufficient O2) C8H18(l) + O2(g) CO2(g) + CO (g) + C (s) + H2O (l) + unburnt hydrocarbons (not balanced) Note the additional products in the incomplete combustion. Extra CO is poisonous, C represents soot and unburnt hydrocarbons from exhaust pollute our cities. Poorly tuned vehicles and inefficient mufflers (loud ones!) result in these problems Source: www.treehugger.com

10. Chemical processes in industry require monitoring and management to maximise production 9.4.2

11. Production of Ammonia – The Haber process In 1912, German scientist, Fritz Haber developed a process for manufacturing ammonia from nitrogen and hydrogen. N2(g) + 3H2(g) 2NH3(g) + 92kJ Notice that this reaction is reversible which can establish equilibrium. This means that Le Chatelier’s Principle applies to the chemistry of this process. Also, note that the forward reaction is exothermic Source: www.bbc.co.uk

12. Schematic of the Haber Process Notice the lack of waste in this process. All unreacted gases are recycled and heat can be collected to be used in the reaction vessel Ammonia is made here Source: Chemistry Contexts 2, 2006

13. Industrial uses of Ammonia • Fertilisers for plants – plants need nitrogen in the form of ammonium and nitrate salts. These are manufactured from ammonia. • Metal extraction – examples are Ni and Au • Cleaning agents • Production a cyanide for plastics manufacturing • Manufacture of synthetic materials such as nylon • Manufacture of explosives • Manufacture of some pharmaceuticals

14. Ammonia and Le chatelier N2(g) + 3H2(g) 2NH3(g) + 92kJ Using your knowledge of Le Chatelier’s Principle, describe what the optimum conditions (in terms of yield and rate) for this reaction will be in relation to the following: • Temperature • Pressure • Use of a catalyst

15. Optimum ammonia production Rate Yield Cost Source: Chemistry Contexts 2, 2006

16. Manufactured products, including food, drugs and household chemicals, are analysed to determine or ensure their chemical composition 9.4.3

17. Atomic Absorption spectroscopy (AAS) Invented by an Australian, this technology is used to detect low concentrations (ppm, ppb) of metal ions in solutions. This is useful in Agriculture and Environmental monitoring. Australian, Alan Walsh invented the first working AAS in 1952

18. Wet chemical Tests for Ions Anions • Cl-, SO42-, CO32-, PO43- • Ppt tests • Ag+ forms insol compounds with chloride, carbonate and phosphate • Ba2+ forms insol compound with sulfate Cations • Ba2+, Ca2+, Cu2+, Pb2+, Fe2+, Fe3+ • Flame tests • See p 218 in text • Ppt tests • HCl forms insolcpd with lead • NH3 forms insolcpd with many others (see flow chart) See exp’t 35 – “Hunt for Ions”