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Identify Raw Materials 1 and 2 and the natural resources from which they are produced. (3)

Identify Raw Materials 1 and 2 and the natural resources from which they are produced. (3). 1 is Calcium carbonate. This is limestone which a common rock and is quarried.

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Identify Raw Materials 1 and 2 and the natural resources from which they are produced. (3)

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  1. Identify Raw Materials 1 and 2 and the natural resources from which they are produced. (3)

  2. 1 is Calcium carbonate. This is limestone which a common rock and is quarried. 2 is concentrated sodium chloride solution (brine). Obtained from injecting hot water to underground salt deposits, salt dissolve and then rises to the surface. Often then purified using fractional crystallisation. Hydroxide added to remove Mg2+.

  3. Construct an equilibrium equation in which sodium hydrogencarbonate is formed and outline the conditions employed to maximise the yield (3) Solvay tower (Ammoniated brine down CO2 up) NH3 + CO2 + H2O > NH4 HCO3 (proton transfer) NOTE: NaCl is present, but at this point only as spectator ions Low temp (high CO2 solubility). High pressure of CO2. Low temperature also promotes crytallisation of NaHCO3

  4. 1- Identify compound X A- NaCO3

  5. During the Solvay process, ammonia is recovered. Outline the recovery of ammonia and suggest TWO reasons why this is desirable A mixture of NH4HCO3 and NaCl is produced from the Solvay Tower.

  6. A mixture of NH4HCO3 and NaCl is produced from the Solvay Tower. When cooled, NaHCO3 precipitates, leaving highly soluble NH4Cl in solution. NH3 is recovered via: 2NH4Cl (aq) + Ca(OH)2(aq)2 NH3 (g)+ CaCl2(aq)+ 2 H2O(l)

  7. This is desirable for two reasons: • So the ammonia can be reused. • So the ammonia is NOT released into the environment.

  8. Identify environmental issues associated with the Solvay Process and evaluate methods of dealing with those issues..

  9. Identify environmental issues associated with the Solvay Process and evaluate methods of dealing with those issues.. • List the major issues first • Waste CaCl2 • NH3 ??? • Thermal pollution • Limestone quarrying • Waste from the limestone kiln

  10. Identify environmental issues and evaluate methods of dealing with those issues.. • CaCl2 waste Australia • CaCl2 is produced as a waste product. Some is recovered but there is not sufficient demand in Australia to take all the CaCl2. • The waste also contains Ca(OH)2 and is slightly alkaline but not to a hamful extent. • Also contained in the waste is NaCl. • As Australia’s only Solvay plant is near the coast. The waste is discharged directly into the ocean. • Na+, Cl- and Ca2+are naturally present in seawater so the discharge of the waste into the ocean causes no significant harm. • OH- ions are neutralised by HCO3-ions that are found in seawater. • OH-+ HCO3-<-> CO32- + H2O • Evalutaion?....

  11. Identify environmental issues and evaluate methods of dealing with those issues.. • CaCl2 waste Overseas • In some countries, Solvay plants have discharged their waste into lakes. Over many years the concentration of Ca2+ and Cl- has increased. • In other countries the waste has contaminated the ground water, raising salinity levels. • Some lakes in other countries have been severely polluted by the discharge of Ca2+ ions. • Discharge into rives would cause significant damage as the salinity of the water would be raised to levels toxic to most freshwater organisms. • Evaluation?

  12. Identify environmental issues and evaluate methods of dealing with those issues.. • NH3 waste. • Ammonia is toxic and would cause significant damage if released into the environment. However, modern plants are very efficient in their recovery of ammonia and virtually none is released. • Evaluation?

  13. Identify environmental issues and evaluate methods of dealing with those issues.. • Thermal pollution • The CaCl2 waste is produced at around 95C and therefore cannot be released directly into the environment. • Cooling towers and heat exchangers are used to lower the temperature • Cooling towers need large volumes of water and so Solvay Plants are located near to large bodies of water. • Discharged waste is only slightly warmer than the environment and has a negligible effect on DO levels, causes no damage to organisms in the food chain and does not accelerate weed or algae growth. • Evaluation?

  14. Identify environmental issues and evaluate methods of dealing with those issues.. • Limestone. • Limestone is mined (normally open cut) this causes environmental damage: habitat destruction, dust, traffic, noise. • Methods to deal with this vary with the location of the mine and depend on local regulations. Sometimes effective, sometimes not. • Decomposition of limestone using coke releases large volumes of CO2, if this is not captured or reused then this contributes to the greenhouse effect.

  15. Identify environmental issues and evaluate methods of dealing with those issues.. • Solid waste products from the limestone kiln. • Non-toxic but can cause huge sludge deposits in waterways, blocking traffic and currents.

  16. Identify environmental issues and evaluate methods of dealing with those issues.. All of these issues are also being addressed by the non-building of new plants, the development of electrochemical methods of production and the refining of impure sources of sodium carbonate (NaHCO3.NaCO3.2H2O)

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