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

Photochemical smog is made up of primary and secondary pollutants.

Extracts from this document...

Introduction

AS CHEMISTRY OPEN BOOK PAPER 2003 Photochemical smog is made up of primary and secondary pollutants Primary pollutants are pollutants released directly into the atmosphere from the combustion of fuels in motor vehicles. Primary pollutants 1 * NOx (a mixture of NO2 and NO), from atmospheric Nitrogen and Oxygen reacting in the heat of car exhausts. * Carbon Monoxide (CO) from incomplete combustion in the engine. * VOC's (volatile organic compounds, mainly hydrocarbons), which are emitted from exhausts as unburnt fuel. When these primary pollutants undergo chemical reactions with each other, and chemicals already present in the atmosphere, they form secondary pollutants. Secondary pollutants 1 * Ozone (O3) * NO2 * Hydrogen peroxide (H2O2) * Peroxy nitrates * Partially oxidised VOC's * Nitric acid (HNO3) Coal-fired power stations and their pollutants Coal-fired power stations also emit primary pollutants: NOx emissions Coal contains nitrogen compounds, from the proteins in the living organisms it was made from. ...read more.

Middle

RCH2 + O2 --> RCH2O2 1 The Peroxy radical then reacts with NO: 6. RCH2O2 + NO --> RCH2O + NO2 1 This reaction converts NO back to NO2, as in the third equation (above), where ozone is used up & re-generated at the same rate. But this reaction does not use up ozone to create the NO2, thus the concentration of ozone rises. The OH radical is formed from ozone: hv O3 --> O2 + O 1 The O atom has high energy, and reacts with water: O + H2O --> 2OH 1 Each Ozone atom creates 2 OH radicals. One OH radical will lead to the production of one O3 molecule through reactions 1,2,4,5, and 6. So the ozone concentration at least doubles. Controlling pollution from coal-fired power stations SOx emissions Sea water scrubbing This is when the flue gases are passed through seawater. Seawater is slightly alkaline and the sulphur dioxide dissolves in it to produce sulphite ions. ...read more.

Conclusion

CH4 --> CO + H2O The alkanes and CO are then reacted with air to combust them completely. This oxidation is exothermic and so produces heat that contributes to the generation of electricity. 4 Gas reburn is a means of achieving NOx reductions and is not an energy saving process in the conventional sense. It is expected that with 19% gas reburn, reductions in NOx emissions of at least 45% from the levels achieved with low NOx burners. 5 Photochemical smog - current research Monitoring Chemists monitor the concentrations of tropospheric pollutants, to study patterns and learn about the rate at which certain reactions will take place in certain conditions. Modelling studies They can put the data into computers, which then simulate the predicted behaviour in specific given photochemical scenarios. The more accurate the information, the better the predictions will be. Smog chamber simulations Primary pollutants are mixed together in a huge clear plastic bag (smog chamber), and exposed to direct sunlight, under carefully controlled conditions. Probes monitor the concentrations of the various components of photochemical smog. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour 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 GCSE Patterns of Behaviour essays

  1. Find out how the rate of hydrolysis of an organic halogen compound depends on ...

    This can be shown as, rate ? [H2O2(aq)] or rate = constant x [H2O2(aq)] Figure 10 Hydrogen peroxide is not the only substance whose concentration affects the rate of this reaction. It is also affected by the concentration of the enzyme catalase, but in the series of experiments shown in Figure 9, the concentration of catalase was kept constant.

  2. Reactivity of the Alkanes

    This is because the bonds between the hexane are fairly strong. There is no sufficient energy provided in this reaction to break the bonds between the hexane so the bromine can bond onto the hexane. > Reagent (bromine) added to hexane with light Bromine is added to hexane and light is applied to this.

  1. How Hitler came to power

    Therefore both the jelly balls and the water will be the same temperature and hopefully give more reliable and accurate results. To ensure my previous method is not right I took a further result at 80 ?C. Temperature of Water (?

  2. Synthesising organic and biochemical compounds- bromobutane.

    I had to remove the stopper before attempting to add more acid. I had to remove the tap funnel and distillation head from the top of the flask and the cooling bath from around the flask. I had to dry the outside of the flask and add a few anti-bumping granules.

  1. Describe, in terms of the production of photochemical smog, what is meant by primary ...

    [2] Other pollutants can also be formed. When incomplete combustion takes place, there is not enough oxygen to make CO2, so carbon monoxide (CO) is formed. Alkane gases are also produced, when the carbon in the coal reacts with hydrogen in the air.

  2. ICT modelling spreadsheet - This coursework was designed to investigate the uses of electricity ...

    To do this, the formula would be '=C(row number) x D(row number)'. To fill in this whole column, quickly and efficiently, rather than just type out each formulae one by one, for over twenty appliances, we could fill in the first entry, '=C4 x D4'.

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