UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE SESI AKADEMIK 2015/2016 : SEMESTER 2 ACADEMIC SESSION 2015/2016 : SEMESTER 2 SCES2211/ SCES2241 : KIMIA ANALISIS I / KIMIA ANALISIS ASAS ANALYTICAL CHEMISTRY I / BASIC ANALYTICAL CHEMISTRY Jun 2016 June 2016 Masa : 2 jam Time : 2 hours ARAHAN KEPADA CALON : INSTRUCTIONS TO CANDIDATES : Kertas soalan ini mengandungi Bahagian A dan B. This paper consists of Section A and 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 8 soalan dalam 6 halaman yang dicetak) (This question paper consists of 8 questions on 6 printed pages)
BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) Jawab semua Empat (4) soalan daripada bahagian ini Answer all Four (4) questions from this section 1. (a) Apakah maksud kimia analisis? What is analytical chemistry? (6 markah/marks) Kecekapan pengekstrakan fasa cecair-cecair boleh diperbaiki melalui pelarasan ph, meningkatkan isipadu fasa organik dan melaksanakan pengekstrakan berbilang. Walau bagaimanapun, usaha untuk meningkatkan isipadu fasa organik bukan satu pendekatan yang praktikal. Bincangkan apakah kelemahan menggunakan teknik ini. The efficiency of liquid-liquid phase extraction can be improved via ph adjustment, increasing the volume of organic phase and performing multiple extractions. However, the attempt of increasing the volume of organic phase is not a practical approach. Discuss what are the disadvantages of using this technique. (4 markah/marks) 2. (a) Untuk teknik kromatografi, respon pengesan dan kesan matriks perlu diambil kira apabila melakukan pengukuran kuantitatif. Apakah maksud respon pengesan dan kesan matriks? For chromatography technique, detector response and matrix effects must take into account when performing quantitative measurement. What does it mean by detector response and matrix effects? (6 markah/marks) Bincangkan apakah empat keseimbangan penting dalam kimia analisis. Discuss what are the four important equilibria in analytical chemistry. (4 markah/marks) 3. (a) Apakah pentitratan kompleksometri? Bincangkan kelebihan menggunakan asid etilenadiaminatetraasetik (EDTA) dalam pentitratan kompleksometri. What is complexometric titration? Discuss the advantages of using ethylenediaminetetraacetic acid (EDTA) in complexometric titration. 2/6
Terangkan mengapa Elektrod Selektif Ion (ISE) mesti ditentukur? Bincangkan dengan terperinci bagaimana ISE boleh ditentukur. Explain why an Ion Selective Electrode (ISE) must be calibrated. Discuss in detail how an ISE can be calibrated. 4. Untuk menganalisis kuprum dalam sampel air alam sekitar, voltammograms kitaran (CV) tidak sesuai digunakan. Bincangkan apakah dua kelemahan utama kaedah ini. Terangkan bagaimana untuk meningkatkan kepekaan dan pemilihan pengesanan kuprum. Apakah teknik elektrokimia lain yang boleh digunakan? For analyzing copper in environmental water samples, cyclic voltammograms (CV) is unlikely to be useful. Discuss what are the two main drawbacks of this method. Explain how to improve the sensitivity and selectivity of copper detection. What are the other electrochemical techniques could be used? 3/6
BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 5. (a) Bezakan antara sampel sambar dan sampel komposit. Distinguish the different between grab sample and composite sample. (4 markah/marks) Suatu loji rawatan kumbahan dikehendaki untuk memantau dan melaporkan purata komposisi air terawat yang dilepaskan ke alam sekitar. Cadangkan satu perancangan sistematik yang sesuai bagi pemantauan perubahan harian terhadap komposisi air terawat ini. A wastewater treatment plant is required to monitor and report the average composition of treated water released to the environment. Suggest an appropriate systematic plan for monitoring the daily changes in the composition of the treated water. (6 markah/marks) (c) Ketumpatan ammonia pekat 20% (berat/berat) ialah 0.899 g/ml. Tentukan isipadu bahan reagen ini yang diperlukan bagi penyediaan suatu larutan NH 3 berkepekatan 0.050 M dalam air menggunakan kelalang volumetrik 250 ml. Diberi jisim molar NH 3 ialah 17 g/mol. The density of concentrated ammonia which is 20% (weight/weight) is 0.899 g/ml. Determine the volume of this reagent required for the preparation of 0.050 M of NH 3 solution in water using 250 ml volumetric flask. Given the molas mass of NH 3 is 17 g/mol. (5 markah/marks) 6. (a) Nyatakan Hukum Beer. Terangkan hubungan di antara transmitan dan keserapan. State Beer s Law. Explain the relationship between transmittance and absorbance (2 markah/marks) Terangkan secara ringkas penyebab kepada sisihan daripada hukum Beer. Briefly describe the causes of deviations from Beer s law. 4/6
(c) Suatu larutan yang mengandungi 3.0 ppm suatu analit (jisim molar = 155 g/mol) mempunyai transmitan sebanyak 65% dalam sel berukuran 1 cm. Hitung keserapan dan keserapan molar bagi analit tersebut. A solution containing 3.0 ppm of an analyte (molar mass = 155 g/mol) has a transmittance of 65% in a 1 cm cell. Calculate the absorbance and the molar absorptivity of the analyte. (3 markah/marks) 7. Lukis dan labelkan gambarajah blok bagi alat UV-Vis spektrofotometer. Terangkan kepentingan setiap komponen utama dalam peralatan ini. Draw and label a block diagram of UV-Vis spectrophotometer. Describe the purpose of each major component of this instrument. 8. (a) Terangkan perbezaan asas antara spektroskopi penyerapan atom dan pemancaran atom. Describe the basic differences between atomic absorption and atomic emission spectroscopy (5 markah/marks) Kandungan plumbum dalam sampel tanah tercemar adalah 10.5, 11.7, 12.0, 10.9 dan 11.6 ppb dalam analisis replikat. Hitung sela keyakinan bagi kandungan plumbum pada aras keyakinan 95%. Lead content in contaminated soil samples were 10.5, 11.7, 12.0, 10.9 and 11.6 ppb in replicate measurements. Calculate confidence interval for lead content at 95% confidence level. (5 markah/marks) 5/6
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