UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE SESI AKADEMIK 2011/2012 : SEMESTER 1 ACADEMIC SESSION 2011/2012 : SEMESTER 1 SCES2243 : KIMIA ALAM SEKITAR AM GENERAL ENVIRONMENTAL CHEMISTRY Januari 2012 January 2012 MASA : 2 jam TIME : 2 hours ARAHAN KEPADA CALON : INSTRUCTIONS TO CANDIDATES: Kertas soalan ini mengandungi Bahagian A and Bahagian B. This question paper consists of Section A and Section B. Jawab soalan mengikut arahan yang diberikan dalam setiap bahagian. Answer the questions according to the instructions given in each section. (Kertas soalan ini mengandungi 11 soalan dan 6 halaman yang dicetak) (This question paper consists of 11 questions on 6 printed pages)
SCES2243/02 BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) Jawab mana-mana LIMA (5) soalan daripada Seksyen ini. Answer any FIVE (5) questions from this Section. 1. Suatu sampel udara pada tekanan 1 atm mempunyai ketumpatan 1.3 g/l dan mengandungi SO 2 pada kepekatan 25 µg/m 3. Apakah kepekatan SO 2 dari segi A particular air sample at 1 atm pressure has a density of 1.3 g/l and contains SO 2 at a concentration of 25 µg/m 3. What is the concentration of SO 2 in terms of (i) (ii) bahagian per juta (jisim SO 2 per 10 6 unit jisim udara)? parts per million (mass of SO 2 per 10 6 units mass of air)? mol SO 2 per 10 6 mol udara? moles SO 2 per 10 6 mol of air? [Diberi/Given 1 atm = 1.013 x 10 2 Pa; R = 8.314 J K -1 mol -1 ; 1.0 m 3 = 10 3 L; T = 298 K; RAM: S = 32.0; O = 16.0] 2. Apakah jisim gas formaldehid, HCHO, yang perlu dibebaskan daripada bangunan, permaidani, dsb. bagi menghasilkan kepekatan 0.5 ppmv bagi gas tersebut dalam suatu bilik yang mempunyai dimensi 4 m x 5 m x 2 m? Dalam kes ini, anggapkan tekanan adalah 1 atm dan suhu 25ºC. What mass of formaldehyde gas, HCHO, must be released from building materials, carpets, etc. in order to produce a concentration of 0.5 ppmv of the gas in a room having dimensions of 4 m x 5 m x 2 m? Assume in this case that the pressure is 1 atm and temperature 25ºC. [Diberi/Given 1 atm = 1.013 x 10 2 Pa; R = 8.314 J K -1 mol -1 ; 1.0 m 3 = 10 3 L; RAM: H = 1.0; C=12.0; O = 16.0]
SCES2243/03 3. Lukis suatu gambarajah profil tenaga untuk tindak balas di antara O 2 dengan N 2 apabila diberi bahawa tindak balas itu adalah endotermik sebanyak 180.8 kj/mol. Pada gambarajah yang sama, tunjukkan profil tenaga bagi tindak balas di antara NO dan O 2, dengan diberi bahawa tindak balas itu eksotermik sebanyak kira-kira 113.2 kj/mol. Daripada profil-profil tersebut, ramalkan mengapa NO tidak bercerai kepada N 2 dan O 2 apabila terbentuk. Draw an energy profile diagram for the reaction of O 2 with N 2, given that the reaction is endothermic by about 180.8 kj/mol. On the same diagram, show the energy profile for the reaction of NO with O 2, given that the reaction is exothermic by about 113.2 kj/mol. From these curves, predict why NO will not dissociate into N 2 and O 2 when formed. 4. Tuliskan siri langkah-langkah di mana gas etilena, H 2 C=CH 2, dioksidakan kepada CO 2 apabila ianya dibebaskan ke atmosfera yang sedang mengalami proses asbut fotokimia. Write the series of steps by which ethylene gas, H 2 C=CH 2, is oxidized to CO 2 when it is released into an atmosphere undergoing a photochemical smog process. 5. Tuliskan persamaan-persamaan yang bersesuaian bagi menggambarkan proses bermangkin yang memusnahkan ozon di stratosfera sebelah bawah. Write down the appropriate equations by which ozone destruction occurs in the lower stratosphere by catalytic process.
SCES2243/04 6. Jadual di bawah memberikan nilai-nilai masa menghuni bagi beberapa pencemar utama udara. Bagaimanakah anda mengaitkan data-data tersebut dengan kereaktifan spesies-spesies tersebut dan kesan alam sekitar mereka. The Table below gives the residence times of some of the major atmospheric pollutants. How do you relate those data with the reactivities of the species and their environmental effects? Spesis/Species Masa menghuni/ Residence time/ Tahun/years N 2 O 20 CO 2, CH 4 3 CO 0.4 SO 2 NO, NO 2 NH 3, H 2 S <0.02 a <0.01 a <0.005 a a Berubah-ubah/ Highly variable. 7. (a) Apakah sumber dan sinki utama bagi N 2 O di atmosfera? What are the main sources and sinks for N 2 O in the atmosphere? Apakah kesan hujan asid ke atas tumbuhan dan hidupan akuatik, contohnya ikan? What are the effects of acid rain on plants and aquatic life, e.g. fish?
SCES2243/05 BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) Jawab SEMUA soalan daripada bahagian ini. Answer ALL questions from this Section. 8. (a) Bincangkan bagaimana ph boleh mempengaruhi cas tanah dan berikan satu contoh bagaimana faktor aktiviti manusia boleh mengubah cas tanah. Discuss how ph affects the charge of soil and give one example how anthropogenic factors can alter the charge of soil? (8 markah/marks) Tanah yang terjejas dengan garam tidak sesuai untuk pertumbuhan pokok. Terangkan. Salt affected soils are not suitable for plant growth? Explain why. (7 markah/marks) 9. (a) Jelaskan kitaran karbon di lautan. Explain carbon cycle in the ocean. Apakah proses amonifikasi dan bincangkan mobiliti ion ammonium dalam tanah. What is ammonification process and discuss the mobility of ammonium ion in soil? 10. (a) Proses penyejatan mempengaruhi komposisi ion Sungai Jordan. Ramalkan nisbah Na/(Na+Ca) bagi sungai tersebut. Beri alasan bagi menyokong jawapan anda. Evaporation process influences the ion composition of Jordan River. Predict the ratio of Na/(Na+Ca) in this river. Give reasons to support your answer.
SCES2243/06 Sungai Columbia mengandungi kepekatan ion Ca 2+ yang tinggi. Nyatakan faktor yang mempengaruhi kepekatan ion tersebut. Beri alasan bagi menyokong jawapan anda. Columbia River contains high concentration of Ca 2+ ion. State the factor that affects the concentration of this ion. Give reasons to support your answer. (c) Terangkan kenapa kepekatan Cl - adalah paling tinggi manakala Si 4+ yang paling rendah dalam air laut sedangkan ion-ion tersebut mempunyai kepekatan yang sama dalam air sungai? Explain why the concentration of Cl - is the highest while Si 4+ is the lowest in sea water even though both the ions have similar concentrations in river water? 11. (a) Terangkan mengapa sungai di kawasan batuan kapur mendapat kurang kesan dari hujan asid berbanding sungai di kawasan granit. Explain why rivers in limestone regions are less affected by acid rain as compared to rivers in granite regions. Bezakan di antara biopemekatan dan biomagnifikasi. Distinguish between bioconcentration and biomagnification. TAMAT END