• 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. 'What problems do urban planners face? How are they to be solved?

    Unfortunately the steel industry collapsed after the global recession after 1973 and was forced to rationalize their resources, which meant widespread job cuts to counteract overproduction. After the steel industry closed 3,750 jobs were lost, with unemployment increasing to around 40%.

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

    Their targets for the government are shown below, and are also compared with hoe well the government mat the targets: * It must promise a doorstep recycling service for every household - it failed to do this but strongly supported doorstep recycling as the way forward.

  1. Atmospheric Pollution – an Environmental Law Essay

    Unfortunately, this is where achievements tend to become more difficult to establish. Early in Labour's first term, Chancellor Gordon Brown took important steps to implement the basic principle of green taxation, that tax should be raised on polluting and environmentally destructive behaviour, with the revenues used to pay for green initiatives and to cut taxes on employment.

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

    In these contexts, such as in Bangladesh, where the people depend on these floods, the prevention of the "hazard" would uproot their way of life. In this way, floods need not always be treated as negative phenomena, causing damage in only certain contexts.

  1. Ozone (O3) is an allotropic form of oxygen with three atoms in each molecule. ...

    Ozone then becomes a secondary pollutant in the formation of photochemical smog, a complex form of air pollution. Ozone can further react with hydrocarbons to form other secondary pollutants such as aldehydes, ketones and peroxyacyl nitrates, all of which are strong oxidants that irritate the eyes and throat.

  2. Pfizer, Kent (UK)The European Headquarters for Research & Development, and the Global Manufacturing main ...

    To allow for future growth and the potential 6.25MVA maximum load, the transformers are designed for a 30% overload using forced cooling. Critical laboratory equipment is supported by a 400kVA UPS unit in a controlled environment within the roof level plant space.

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

    the city, and others around the suburbs or through the city centre. Each type of route was connected to one another, meaning people could get from rural areas to the CBD in a series of quick, efficient bus journeys, making Curitiba?s system unrivalled in terms of its integration and convenience.

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

    The vast majority of these potatoes are grown here in the UK. All the burgers that are provided by McDonald?s are from 100% meat that is supplied by farms that are qualified by nationally recognised farm assurance scheme. Battery farming is an industrial agricultural confinement system that is used primarily for egg-laying hens.

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