N 2 O Hv N 2 O example essay topic

GREENHOUSE EFFECT CONTENT 1. Introduction 1.1 Definition of Greenhouse Effect 1.2 History Background 1.3 Why Social Relevance 2. Chemical Significance 2.1 Carbon Dioxide 2.2 Methane 2.3 Nitrous Oxide 2.4 Chlorofluorocarbons Bibliography Draft References 1. Introduction 1.1 Natural Greenhouse Effect [1, 2, 3, 4, 5] The natural greenhouse effect is the heating of the Earth due to the presence of greenhouse gases.

Shorter-wavelength solar radiation from the sun passes through the Earth's atmosphere, and is then absorbed by the surface of the Earth, causing it to warm. Part of this absorbed energy is then reradiate d back to the atmosphere as longer-wavelength infrared radiation. Most of this infrared waves is absorbed by the greenhouse gases, thus heating the Earth. 1.2 Enhanced Greenhouse Effect [1, 2, 3, 5, 6] The increasing concentration of these greenhouse gases have resulted in increased absorption of infrared radiation emitted from the Earth's surface thus increasing the overall temperature of the Earth, creating the enhanced greenhouse effect. 1.3 History Background [1, 4, 7] The Industrial Revolution brought steam trains and factories that burnt wood or coal to supply energy that was later followed by petrol, diesel and oil as energy sources. Practices of the Industrial Revolution greatly increased the amount of greenhouse gases concentration thus, increasing the amount of heat energy that is trapped in the atmosphere.

Therefore, the formulation of the enhanced greenhouse effect is increased. 1.4 Social Relevance [1, 5, 8] Global warming caused by the greenhouse effect is a concern to society. The problem influences health, agriculture, environment and other aspects. Therefore, it is important to understand this chemical significance of greenhouse gases and its formation to solve these problems. 2. Chemical Significance 2.1 Carbon Dioxide [ 3, 4, 6] Carbon dioxide (CO 2) is a colourless, odour less and non-flammable gas and is the most prominent greenhouse gas in the Earth's atmosphere.

Fossil fuel burning and large-scale deforestation causes the increase in CO 2. C + O 2 CO 2 CH 4 + 2 O 2 CO 2 + 2 H 2 OThe concentration of CO 2 has increased from 290 pp mv to 380 pp mv after the Industrial Revolution. Carbon dioxide is on the rise since 17502.2 Methane [3, 4, 6] Methane (CH 4) is a colourless, odour less and flammable gas. It is 20 times more powerful than CO 2 as a greenhouse gas on a weight to weight basis. Its concentration has increased from 700 ppb vs. to 1720 ppb vs. throughout the twentieth century due to fossil fuel mining, agricultural practices and decomposition of organic compounds.

CH 4 can be destroyed in the atmosphere via reaction with the hydroxyl radical. The mean atmospheric lifetime of CH 4 is about 8 years. CH 4 + OH CH 3 + H 2 O Methane is on the rise since 1750 2.3 Nitrous Oxide (Laughing Gas) [3, 4, 6] Nitrous Oxide (N 2 O) is an odour less gas. It is 200 times more powerful as a greenhouse gas than CO 2. The main sources of N 2 O created by human activity are from agriculture, biomass burning and industrial processes. N 2 O is destroyed in the stratosphere via photolysis by solar radiation and by reaction with excited atomic oxygen.

The mean lifetime of N 2 O in the atmosphere is about 150 years. N 2 O + hv N 2 + O, 341 non 2 O + O N 2 + O 2 N 2 O + O 2 NO Nitrous Oxide has been on the rise since 1750 2.4 Chlorofluorocarbons (CFC-11 and CFC-12) [3, 4] Chlorofluorocarbons are widely used for propellants, refrigerants and foaming agents. CFC-11 and CFC-12 are destroyed by photolysis by solar radiation and by reaction with excited atomic oxygen. CCl 3 F + hv CCl 2 F + Cl, 265 nmCCl 2 F 2 + hv CCl 3 F 2 + Cl, 200 nmCCl 3 F + O CCl 2 F + ClO CCl 2 F 2 + O Ccl + ClO 2.5 Water vapour [6] Warming due to increases in other greenhouse gases is likely to increase the evaporation rate of water thus, increasing the amount of water vapour in the atmosphere, adding to global warming. (675 words)

Bibliography

Books: 1. Discovering Chemistry (2000), pg.
142-1442. Same - Stage 2 Chemistry The Essentials (2002), pg.