ALS14Q(ENVIRONMENT)

ALS14Q(ENVIRONMENT) - Section 14.1/ Chemistry and the...

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Section 14.1/ Chemistry and the environment / SKH Bishop Baker Secondary School AL Chemistry Section 14 Chemistry and Society (14.1 Chemistry and the environment) AS94A Q.6 (a) Chlorofluorocarbons (CFCs) was once widely used in developed countries but recently these countries have agreed to ban the use of CFCs by the end of this century. (i) State TWO major uses of CFCs. (ii) Even though CFCs are useful chemicals, it is necessary to ban their use. Why? (4 marks) (b) The table below shows the mean SO 2 and NO 2 levels, in p.p.m. (parts per million), recorded by three air-monitoring stations in three areas, Tsuen Wan, Hong Kong South and Sham Shui Po in 1991. Area SO 2 level/p.p.m. NO 2 level/p.p.m. Tsuen Wan 0.0130 0.031 Hong Kong South 0.0026 0.011 Sham Shui Po 0.0038 0.026 (i) What is the meaning of the unit ‘p.p.m.’ in the above table ? (ii) Which of the above areas has the poorest air quality ? Give reasons for the poor air quality of this area. (iii) Suggest ONE measure to improve the air quality in Hong Kong. (4 marks) AS94A Q.7 (III) Chemistry and home hygiene (b) (i) Most washing powders contain phosphates of sodium. Give ONE reason for the inclusion of phosphates of sodium. Give ONE environmental problem that is caused by the excessive use of phosphate-containing washing powder. (2 marks) AS94B Q.8 (a) Briefly explain each of the following observations and the underlying chemical principles. (ii) Rainwater collected in the countryside is not neutral but is slightly acidic (pH about 5.6), while that collected in an industrial area is even more acidic (pH less than 4.8). 1
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Section 14.1/ Chemistry and the environment / AS94C Q.14 Environmental problems in Hong Kong are of great complexity. Discuss the above statement by making reference to the causes of the different types of pollution, the adverse effects on the environment of the pollutants concerned, and the control measures that are being taken in Hong Kong. (15 marks) AS95B Q.11 (b) Some of the water quality standards in a certain country are listed below. pH range : 6.0 9.0 Dissolved oxygen (DO) : not less than 4 mg dm -3 Biochemical oxygen demand (BOD) : not more than 5 mg dm -3 (i) To meet the water quality standards in this country, what is the proper way of treating the waste water which is strongly acidic before it is being discharged ? (ii) What are the consequence if the dissolved oxygen (DO) in a river is less than 4 mg dm - 3 ? Explain your answer. (iii) What is meant by the term ‘biochemical oxygen demand’ (BOD) ? Why does the waste water discharged from a pig farm usually have a BOD higher than 5 mg dm - 3 ? (iv) Outline how waste water can be treated in a sewage treatment plant so as to bring its BOD to the required standard. (8 marks)
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This note was uploaded on 08/17/2011 for the course CHEM 100 taught by Professor Fleet during the Fall '08 term at Oxford University.

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ALS14Q(ENVIRONMENT) - Section 14.1/ Chemistry and the...

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