phenomenon. It occurs as a result of the way the Earth\'s atmosphere interacts w
ID: 1044543 • Letter: P
Question
phenomenon. It occurs as a result of the way the Earth's atmosphere interacts with radiation from and to space. ? Explain why certain gases, such as CO2 and CHa are able to absorb anfrared adiation but other gases, such as N2 and O2, are not ii Explain how dhe greenhouse effect warms the Earth. ii Explain why buman activity may be increasing the effect of the natural greenhouse effect and 131 state one consequence of this. Explain how both of the following statements can be true. 141 131 121 b I Carbon dioxide is the most important greenhouse gas. II Methane is a much more important greenhouse gas than carbon dioaxide. e Explain what is meant by 'global dimming. 121 Batteries are portable sources of electricity that have become increasingly important as we rely more and more on portable electronic devices a Explain in what way a bigger battery may be better than a smaller one of the same type b A nickel-cadmium battery is a ype of rechargeable battery often used instead of primary cells in HL 6 devices such as portable radios. i Explain the difference between a primary cell and a rechargeable cell. ii Write equations for the reactions that occur at the anode and cathode when a nickel-cadmium 12] 31 battery is discharged and state which involves oxidation and which reduction Fuels cells and rechargeable batteries have both been considered as the power source Explain why lead-acid batteries are not suitable as the main power source for an electric vehide. A student carried out an experiment to measure sandard clectrode potentials by comparing half-cells to a reference electrode. She obtained the value 0.32V for the electrode potential of the Cu (a)Cu standard electrode potential is 0.34V. In the conclusion to her to the litenature walue because the electrode potential saries with concentration and tempenatare, and therefone beanse the temperatore for electric vehicles e d o) half cell She looked up some literature values and found that che accepted valse for chis experiment, she stated, 'my value is different in the room where I carried out the experiment uNE 19 C and the concentration of copper sullate this explains any diference between may value and the litenature alue.'Comment on this statement and carry out a calculation to back up your explanation. HL 7 Nuclear fusion has the potential to produce vast amounts of energy 121 a State what is meant by the terms 'mass defect' and'nuclear binding energy' b Explain why H has a nuclear binding energy of zero c Tritium GH) is an isotope of hydrogen. Given the data in the table, calculate i the mass of a tritium nucleus in unified atomic mass units the mass defect in kg the nuclear binding energy per nucleon of a tritium nucleus in J. 12 12) iii Mass/u 1,007 276 1.008665 0.000 5486 proton electron tritium atom 3.01605 helium atom 4.002 60 CHEMISTRY FOR THE IB DIPLOMA CAMBRIDGE UNIVERSITY PRESS 2014 C ENERGYExplanation / Answer
5. a.
i) Certain gases can absorb and re-emit infrared (IR) radiation (eg; CO2). But gases such as N2 or O2 can’t absorb it. If the frequency of IR radiation matches with that of vibrational modes of the molecule then it absorb the radiation. The gases like CO2 absorb energy from IR radiation and this causes molecule to vibrate. The molecules which can change dipole moment during vibration can only absorb IR radiation. So the non polar N2 or O2 can’t absorb it.
ii) The sunrays come to earth and warm the earth. Most of rays return back to space. But the green house gases traps it. It absorbs certain kind of radiations (IR) and re-emits to earth surface. By this process the radiation (heat) stay in earth itself. This makes earth warm. This is a natural process. Without this process earth would have been very cold.
iii) Human activities produce large quantity of variety of greenhouse gases and it increases the natural green house effect. Burning of fossil fuels, deforestation, disposal of garbage and human waste and industrial process emit large amount of carbon dioxide. Industry also produces chlorofluorocarbons (CFC) and other halo compounds which are green house gases. Fertilizer use increases emission of nitrous oxide. Thus human activity increases the production of green house gases and thereby green house effect. The most important consequence of this is global warming. As the amount of green house gases increases the heat trapped in the atmosphere also increases and this leads to global warming.
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