UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS DENGAN PENDIDIKAN EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE WITH EDUCATION SESI AKADEMIK 2012/2013 : SEMESTER 2 ACADEMIC SESSION 2012/2013 : SEMESTER 2 SCES2245 : PENGENALAN KEPADA KIMIA ANALISIS INTRODUCTION TO ANALYTICAL CHEMISTRY Jun 2013 June 2013 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 7 soalan dalam 7 halaman yang dicetak) (This question paper consists of 7 questions on 7 printed pages)
BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) Answer ALL questions from this Section. Jawab SEMUA soalan daripada bahagian ini. 1. (a) Terdapat selisih jitu dalam pengukuran ion fluorida pada ph < 5 dan > 8 apabila elektrod ion tentu digunakan untuk mengukur. Terangkan. There is an error in the measurement of fluoride ion at ph < 5 and > 8 when an ion selective electrode is used to measure. Explain. (6 markah/marks) Terangkan selisih alkali dan selisih asid bagi elektrod ph kaca. Describe the alkaline error and the acid error of a ph glass electrode. (6 markah/marks) 2. (a) Apakah fungsi elektrolit pembantu dalam kaedah voltammetrik? What is the function of the supporting electrolyte in voltammetric method? Nyatakan kelebihan dan kekurangan elektrod titis merkuri berbanding elektrod platinum atau carbon. List the advantages and disadvantages of the dropping mercury electrode compared with the platinum or carbon electrodes. (8 markah/marks) 3. (a) Jelaskan mengapa agen pengkelatan diperlukan bagi pengekstrakan ion logam dalam sistem pengekstrakan pelarut. Explain why a chelating agent is needed for extraction of metal ions in solvent extraction systems. Terangkan prinsip asas bagi gas kromatografi. Describe the basic principles of gas chromatography. 2/7
(c) Terangkan bagaimana temperature programming dapat memperbaiki pemisahan dalam kromatografi gas. How does temperature programming improve separations in gas chromatography? (d) Terangkan prinsip bagi pengesan kromatografi gas berikut: Describe the principle of the following gas chromatography detectors: (i) (ii) konduktiviti terma thermal conductivity pengionan nyala flame ionization (10 markah/marks) 3/7
Answer ALL questions in this section. Jawab SEMUA soalan dalam bahagian ini. BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) 4. (a) Terangkan secara ringkas perbezaan di antara setiap daripada dua istilah di bawah: Explain briefly the differences between each of the following pair of terms: (i) (ii) (iii) (iv) Analisis kuantitatif dan kualitatif Quantitative and qualitative analysis Ketepatan dan kejituan Accuracy and precission Ralat peralatan dan ralat kaedah Instrumental and method error Kaedah volumetrik dan gravimetrik Volumetric and gravimetic method (12 markah/marks) Terangkan penyediaan larutan 500 ml larutan asid hidroklorik (HCl) dengan kepekatan 0.10 M daripada asid hidroklorik pekat 37.5% (b/b). [Jisim molar HCl = 36.46 g mol -1 dan ketumpatan HCl pekat 37.5% = 1.1866 g cm -3 ] Describe how you would prepare a 500 ml of 0.10 M hydrochloric acid (HCl) solution from concentrated hydrochloric acid 37.5% (w/w). [Given the molar mass of HCl = 36.46 g mol -1 and the density of 37.5% HCl =1.1866 g cm -3 ] (8 markah/marks) 4/7
5. Penguraian sukrosa oleh enzim invertase menghasilkan glukosa and fruktosa Sukrosa Enzim invertase Glukosa + Fruktosa Kaedah berikut digunakan untuk menentukan kandungan sukrosa dalam betik. Satu sample betik dengan berat 99.8 g dikisar dan diperah untuk mendapatkan 500.0 ml jus. Kemudian, analisis kandungan glukosa dilakukan ke atas beberapa sampel jus yang berisipadu 5.00 ml dengan menggunakan kaedah spektroskopik. Tanpa menggunakan enzim, kepekatan glukosa bebas ditentukan. Keputusan daripada lima penentuan menunjukkan kandungan glukosa bebas adalah 1108 mg/l, 1095 mg/l, 1098 mg/l, 1100 mg/l, and 1109 mg/l. Selepas itu, enzim invertase ditambahkan ke dalam 5 sampel jus yang lain. Selepas 20 minit, kandungan glukosa ditentukan. Keputusan menunjukkan kandungan glukosa adalah 2657 mg/l, 2658 mg/l, 2669 mg/l, 2648 mg/l, and 2642 mg/l. Sucrose can be broken down into glucose and fructose by enzyme invertase. Sucrose Enzyme invertase Glucose + Fructose The following procedure was used to determine the sucrose content of papaya. A 99.8 g of papaya sample was chopped into pieces and the juice was carefully collected along with a lot of water (for washing) to form a final solution with the volume of 500 ml. Several 5.00 ml aliquots were taken and analyzed by a spectroscopic method for glucose. Sample without any added enzyme was used to determine the free glucose concentrations. Five trials of this analysis gave the following concentrations: 1108 mg/l, 1095 mg/l, 1098 mg/l, 1100 mg/l, and 1109 mg/l. Then, enzyme invertase was added to another five aliquots and after 20 minutes, they were also analyzed for glucose, giving the following concentrations: 2657 mg/l, 2658 mg/l, 2669 mg/l, 2648 mg/l, and 2642 mg/l. (a) Tentukan kepekatan purata glukosa yang dihasilkan daripada penguraian sukrosa. What is the average concentration of glucose from the decomposition of sucrose in papaya? Tentukan peratusan sukrosa (b/b) dalam betik. [Molar untuk glukosa = 180.16 g/mol dan jisim molar untuk sukrosa = 342.34 g/mol] What is the percent sucrose (w/w) in the papaya? [Molar mass of glucose = 180.16 g/mol and molar mass of sucrose = 342.34 g/mol] (10 markah/marks) 5/7
6. (a) Lakarkan gambarajah blok bagi spektrofotometer alur tunggal dan terangkan secara ringkas fungsi setiap komponen utama dalam peralatan ini. Draw a block diagram of a single beam spectrophotometer and describe briefly the function of each basic component of this instrument. Spektroskopi penyerapan atom nyala merupakan teknik yang biasanya digunakan untuk menentukan logam dalam sampel air. Terangkan prinsip teknik ini. Flame atomic absorption spectroscopy (FAAS) is a common technique for the determination of metals in water samples. Describe briefly the principle of this technique. (7 markah/marks) 7. Kepekatan (mg/l) berikut diperolehi daripada penentuan ion kalsium dalam air. The following concentrations (mg/l) were obtained from the determination of calcium ion in water. Tentukan Determine 2.37 2.49 2.21 2.42 2.35 2.50 (a) purata dan sisihan piawai bagi data di atas, mean and standard deviation for the above data, (4 markah/marks) nilai purata bagi data yang diperolehi daripada kaedah ini pada paras keyakinan 95%. the mean of the measurement obtained by this method at 95% confidence interval. (4 markah/marks) 6/7
TAMAT 7/7
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