Chemical Monitoring and Management. Flashcards
Identify that Ammonia can be synthesised from its component gases, Nitrogen and Hydrogen.
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Identify and describe the industrial uses of Ammonia.
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Identify that the production of Ammonia occurs as a reversible reaction that will reach equilibrium.
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Explain why the rate of reaction in the production of Ammonia increases at higher temperatures.
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Explain why the yield of the product in the Harber process is reduced at higher temperatures using Le Chatelier’s principle.
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Explain why the monitoring of the reaction vessel in the Harber process is crucial and discuss the monitoring required.
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Describe an example of a chemical reaction such as combustion, where reactants form different products under different conditions and would thus need monitoring.
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Describe the use of Atomic Absorption Spectroscopy in detecting concentrations of metal ions in solutions and asses its impact on on scientific understanding of the effects of trace elements.
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Identify alternative chemicals used to replace CFC’s and evaluate the effectiveness of their use as a replacement for CFC’s.
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- Hydroflurocarbons (HFC’s):
- Contain carbon- hydrogen bonds that cause them to undergo some decomposition in the troposphere, and contain no carbon- chlorine bonds that would form chlorine free radicals in the stratosphere. Thus, the ozone destroying capacity of HFC’s is zero.
- HFC’s are more chemically and thermally stable than CFC’s, reflecting the inertness of the C-F bond.
- Because of the reduced intermolecular Van Der Waals interactions, HFC’s are often lubricants or are highly volatile.
- Gas soluble flurocarbon liquids have medical applications.
- Hydrochloroflurocarbon (HCFC):
- A haloalkane containing hydrogen, chlorine and fluorine atoms.
- The carbon- hydrogen bonds in HCFC’s are susceptible to attack by reactive radicals and atoms in the troposphere, and are therefore decomposed there to a significant extent.
- They diffuse into the stratosphere and cause ozone reduction.
Gather, process and present information to describe and explain evidence for the need to monitor levels of lead as used in society.
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- Lead is a heavy, toxic chemical.
- Inhibits the production of haemoglobin in the bloodstream.
- It accumulates in an organimsim, leading to bioaccumulation.
Gather, process and present information on the range and chemistry of the tests used to identify heavy metal pollution of water and monitor possible eutrophication of waterways.
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- Heavy Metals:
- Are a metal with a relative density of 5.0 or higher.
- Heavy metal pollution of water can be tested using:
- Atomic absorption spectroscopy.
- Flame tests.
- Sodium sulfide solution, which can be added to a highly concentrated acidified or basified water sample (heavy metal ions react with sulfide ions to form sulfide precipitates).
- If a precipitate is formed when the sample is acidified, then one or more of the following is present; lead, silver, mercury, copper, cadmium, arsenic.
- If a precipitate is formed when the sample is basified, then one or more of the following is present; chromium, zinc, iron (III), nickel, cobalt, manganese, aluminium.
- Eutrophication:
- The abundant growth of aquatic plants due to nutrient enriched conditions, in particular, nitrate and phosphate enrich conditions.
- The aquatic plants that grow abundantly in eutrophication eventually use up all of the available nutrients and die.
- The decompose, and in doing so, use up all dissolved oxygen.
- After using all oxygen, they decay anaerobically resulting in chemicals that kill all remaining life.
- The decay causes sediment at the bottom of the water body.
- The main sources of nutrients that cause eutrophication are; sewerage and fertiliser.
- Nitrate and phosphate are monitored in waterways vulnerable to eutrophication.
Describe the conditions under which Harber developed the industrial synthesis of ammonia and evaluate its significance at that time in world history.
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- Fritz Harber developed the Harber process in the beginning of the twentieth century, leading up to the First World War.
- At this time nations such as Germany imported the nitrates that they required for fertilisers and explosives from South America.
- Growing world populations were placing strain on the natural resource.
- In Germany, the growing militancy was promoting calls for more explosives, creating further demand for natural nitrate resources.
- In 1908, Harber developed a catalytic method of synthesising ammonia from its elements.
- The Harber process allowed for the production of fertilisers and explosives to continue in Germany, sustaining the war effort and prolonged it.
