• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

In urban areas like London motor vehicles, amongst other sources, are the main cause of air pollution. Photochemical reactions produce a cloud of toxic chemicals including ozone and a variety of caustic agents.

Extracts from this document...

Introduction

SALTERS CHEMISTRY OPEN-BOOK PAPER In urban areas like London motor vehicles, amongst other sources, are the main cause of air pollution. Photochemical reactions produce a cloud of toxic chemicals including ozone and a variety of caustic agents. This is often covering whole cities a photochemical smog. This photochemical smog consists of two criteria of pollutants: primary and secondary pollutants. Primary pollutants are emitted directly from their sources into the atmosphere. Examples of primary pollutants include: carbon monoxide (CO), NOx, sulphur dioxide (SO2), and various hydrocarbons (HxCy), also known as volatile organic compounds (VOC). The prime source of air emissions generated by motor vehicles such as truck diesel emissions is CO, NOx and HxCy Secondary pollutants can be produced over a period of time when photochemical reactions take place in the atmosphere. An example of a secondary pollutant is ozone (O3), which is one of the products formed when NOx react with hydrocarbons (from motor vehicles), in the presence of sunlight. ...read more.

Middle

Below are the outlines of the processes required for the formation of the two most dominant toxic components: ozone and peroxyacetyl nitrate. R represents a hydrocarbon which is primarily created from volatile organic compounds. Nitrogen dioxide can be formed by one of the following reactions. Nitrogen oxide acts to remove ozone from the atmosphere. This mechanism occurs naturally in an unpolluted atmosphere. Formulae adapted from 'Photochemical smog: the killer on a summer's day' O3 + NO O2 + O2 NO2 + RO2 NO2 + other products Sunlight can break down nitrogen dioxide back to nitrogen oxide. NO2 + sunlight NO + O The atomic oxygen formed in the above reaction then reacts with one of the abundant oxygen molecules producing ozone. O + O2 O3 Nitrogen dioxide can also react with radicals produced from the volatile organic compounds in a series of reactions to form toxic products such as peroxyacetyl nitrates (P.A.Ns). NO2 + R products such as P.A.Ns Ozone can be produced naturally in an unpolluted atmosphere. However, it is consumed by nitrogen oxide as illustrated in the first reaction. ...read more.

Conclusion

NOx moving upward from coal combustion in the lower furnace is stripped of oxygen as the reburn fuel is partially combusted in the reburn zone and converted to molecular nitrogen. Over fire air ports above the reburn zone provide for complete combustion in a relatively cooler region of the boiler. Reburning allows the low-NOx burners to operate at excess air levels far below that needed for complete combustion, thus enhancing their effectiveness. The synergistic effect of adding a reburning stage to wall-fired boilers equipped with low-NOx burners was intended to lower NOx emissions by up to 70%. This was probably chosen because it produces heat that can be used to generate even more electricity. The end product of this process is summarised below. Formula from 'Longannet: clean coal power?' CH4(g) + 4NO(g) 2N2(g) + CO2(g) + 2H2O(g) Adapted from http://www.lanl.gov/projects/cctc/factsheets/eerco/images/eerco_schematic.jpg Diagram of gas reburn The part played by chemists in their research is that they implement experiments to predict rate of reactions in different conditions. They do this though modelling studies and smog chamber simulations. Ultimately they are researching to combat pollution through burning fossil fuels. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Environmental Management section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Environmental Management essays

  1. How Does Air Pollution Affect the Hong Kong People and Economy?

    The marginal social benefit curve shows how much more benefit society as a whole will gain from one extra unit. The marginal social cost curve shows the extra cost to society as a whole of this extra unit. If the MSB is greater than MSC, then it would be beneficial to increase the consumption (positive externalities).

  2. I am going to research waste pollution. I have chosen to research waste pollution ...

    Also the current practise of landfilling mixed municipal waste is highly polluting, as well as unpopular and ultimately unsustainable. To stop waste pollution the pressure group set targets for the government, take action against incineration and also campaign against landfills which are affecting the environment.

  1. The main aim of hazard management should be to reduce the effects of hazards, ...

    elderly did not want evacuate, because of fear of new living conditions, or that they do not want to leave their home. This contributed to the majority of the deaths being the elderly in these events. Thus, changing the perceptions of various peoples in different cultural contexts plays a large

  2. Pollution. The main sources of these pollutants are industrial factories and motor vehicles. The ...

    Air pollution is one of many forms of global pollutions here on the planet. Water is another big medium for pollution which people cannot live without. People take very little precautions with the water they drink in turn it leads to waterborne diseases being transmitted to persons; water is so

  1. Smog. Photochemical smog poses easily the biggest threat to clean air in Australia and ...

    Ground level ozone concentrations are measured nationwide (CSIRO uses Airtrak pollution measurement system and a process called chemiluminescence).These concentrations, which are available at the government websites, can be linked to particular descriptors of air quality (see Table1). The ozone and nitrogen dioxides found in the photochemical smog can do a

  2. Cars offer fast reliable transportation, offering drivers access to anywhere with roads, but there ...

    Playing an important role in absorbing radiation from the sun. Protecting us from ultra violet rays. Without an ozone layer these rays would effect humans with non-melanoma skin cancer, as well as damaging plant life, marine life, and animal life.

  1. I am researching about four organisations energy policies which are: McDonalds, Tescos, EDF Energy ...

    Taken from: http://www.mcdonalds.co.uk/ourworld/environment/packaging.shtml - Author - IPL Perseco, McDonald's packaging supplier Accessed on 17/10/2011 This shows that the policy that McDonalds has carried out in practice is successful because in 2007 they proved than more than 80% of all packaging used by McDonald?s UK was made from renewable resources and

  2. With reference to transport management in urban areas, discuss the extent to which sustainability ...

    people in his decisions and aimed to meet human needs, thus making Curitiba more sustainable. Curitiba?s success could be attributed to near full integration in its transport system. Lerner?s vision was based mostly on the use of public buses in order to achieve sustainability; this method was 500x cheaper than an underground subway system, suggesting economic sustainability.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work