SCES1200 : PRINCIPLES OF CHEMISTRY PRINSIP-PRINSIP KIMIA

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1 UNIVERSITY OF MALAYA UNIVERSITI MALAYA EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE WITH EDUCATION PEPERIKSAAN IJAZAH SARJANA MUDA SAINS DENGAN PENDIDIKAN ACADEMIC SESSION 2012/2013 : SEMESTER 1 SESI AKADEMIK 2012/2013 : SEMESTER 1 SCES1200 : PRINCIPLES OF CHEMISTRY PRINSIP-PRINSIP KIMIA January 2013 Januari 2013 TIME : 2 hours MASA : 2 jam INSTRUCTIONS TO CANDIDATES : ARAHAN KEPADA CALON : This paper consists of Section A and B. Kertas soalan ini mengandungi Bahagian A dan B. Questions should be answered according to the instructions given in each section. Jawab soalan mengikut arahan yang diberikan dalam setiap bahagian. (This question paper consists of 4 questions on 6 printed pages) (Kertas soalan ini mengandungi 4 soalan dalam 6 halaman yang dicetak)

2 SCES1200/ 02 BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 1. (a) Discuss the postulates in Bohr atomic model, and compare these to the Schrödinger atomic model. Bincangkan postulat dalam model atom Bohr dan bandingkan dengan model atom Schödinger. (b) The emission spectrum of hydrogen gas may be given by one of the following sketches. Choose the most correct one and explain your choice. Spektra emisi gas hidrogen diberikan diantara rajah di bawah. Pilih yang betul dan terangkan pilihan anda. Increasing frequency (4 marks/markah) (c) Calculate the uncertainty in speed of an electron if its position in space is known within the range of 2 pm. Assume m e = 9 x kg. Kira ketidakpastian halaju bagi satu elektron jika kedudukannya dalam ruang diketahui dalam jarak 2pm. Andaikan m e = 9x kg.

3 SCES1200/ 03 (d) The ground-state electronic configurations of five elements (i-v) are given below, Konfigurasi electron paras terendah bagi lima elemen diberikan di bawah, i. 1s 2 2s 2 2p 6 3p 6 3d 5 4s 2 ii. 1s 2 2s 2 2p 6 3s 2 iii. 1s 2 2s 2 2p 6 iv. 1s 2 2s 2 2p 6 3s 2 3p 2 v. 1s 2 2s 1 Select amongst (i-v), which electronic configuration, Pilih yang manakah di antara (i-v), konfigurasi electron represents a noble gas; yang mewakili gas nadir; is most likely to form an oxide with catalytic properties; yang mungkin membentuk oksida dengan sifat mangkin; and will have the highest first ionization energy of the elements in the GROUP which it is found. dan yang mempunyai tenaga pengionian unsur tertinggi dalam Kumpulannya. Name the chosen elements and explain your choice. Namakan unsur-unsur yang dipilih dan terangkan pilihan anda. (6 marks/markah) 2. (a) Determine the number of modes of motion for translation, rotation and vibration for the molecules CO 2, NH 3 and C 6 H 6. Calculate their average kinetic energies and give your assumptions. Tentukan jumlah mod gerakan bagi translasi, putaran dan getaran. Bagi molekul berikut, CO 2, NH 3, C 6 H 6. Kira purata tenaga kinetik bagi setiapnya dan nyatakan andaian yang anda gunakan.

4 SCES1200/ 04 (b) Calculate the average velocity of methane gas at 300K. [R = kg m 2 s -2 K -1 mol -1 ; relative atomic mass: C = 12.0; H = 1.0]. Hitung purata halaju bagi gas methana pada 300K. [R = kg m 2 s -2 K -1 mol -1 ; jisim atom relatif: C = 14.0; H = 1.0]. (c) The distribution of speed of CO gas at 0 C, 1,000 C and 2,000 C are given as follows. Gambar rajah taburan halaju bagi gas CO pada 0 C, 1,000 C dan 2,000 C diberikan. Explain the factors influencing this distribution for CO gas. Give all assumptions for this distribution model. On the graph for 1,000 C, mark the positions of average velocity and the root mean square velocity. Terangkan faktor-faktor yang mempengaruhi taburan bagi gas CO. Beri semua andaian untuk model taburan ini. Pada geraf bagi 1,000 C, tandakan kedudukan halaju purata dan halaju punca-kuasa dua.

5 SCES1200/ 05 BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 3. (a) Name the elements that have the following symbols: Pr, Nd, Rb, Ga and In. Namakan unsur-unsur yang memakai simbol-simbol berikut: Pr, Nd, Rb, Ga and In. (b) What are the chalcogens? Name the elements of this group. Apakah calkogen? Namakan unsur-unsur dalam kumpulan ini. (c) Calculate the effective nuclear charge for sodium. (Na 1s 2 2s 2 2p 6 3s 1 ) Hitungkan cas nucklear berkesan natrium. (Na 1s 2 2s 2 2p 6 3s 1 ) (d) Be atom has a radius of 0.90Ǻ while its cation Be 2+ has a radius of 0.31 Ǻ. Explain the differences. Atom Be mempunyai jejari 0.90 Ǻ manakala ionnya, Be 2+, mempunyai jejari 0.31 Ǻ. Terangkan perbezaannya. (e) Define electronegativity. Describe and explain the trend in electronegativity values as one descends a group of the periodic table. Takrifkan keelektronegatifan. Hurai dan terangkan tren didalam keelektronegatifan jika anda menuruni kumpulan dalam jadual berkala. (f) Describe the physical properties of Group 14 (IVA),(C, Si, Ge,Sn & Pb), elements. Huraikan sifat fizikal unsur-unsur Kumpulan 14(IVA), (C, Si, Ge,Sn & Pb)

6 SCES1200/ (a) Balance the following equation: Cr 2 O 7 + C 2 O 4 Cr 3+ + CO 2 (in acidic condition) Imbangkan persamaan berikut: Cr 2 O 7 + C 2 O 4 Cr 3+ + CO 2 (dalam keadaan berasid) (3 marks/markah) (b) Aluminium metal reacts with iron(iii) oxide to produce aluminium oxide and iron metal. Logam aluminium bertindakbalas dengan ferum(iii) oxida bagi menghasilkan aluminium oksida dan logam ferum. (i) (ii) (iii) (iv) Write an equation to show the above reaction. Tuliskan persamaan yang menunjukkan tindakbalas diatas. How many moles of Fe 2 O 3 are needed to react completely with 30 g of Al? Berapakah mol Fe 2 O 3 diperlukan bagi menindakbalas sepenuhnya dengan 30g Al? How many moles of Fe are produced by the reaction of 2.80 mol of Fe 2 O 3 and 80.0 g of Al? Berapakah mol Fe dihasilkan oleh tindakbalas 2.80 mol Fe 2 O 3 dan 80.0g Al? How many atoms of Al are required to produce 6.4g of Fe? Berapakah atom Al diperlukan bagi menghasilkan 6.4g Fe? (Fe = 55.8 Al= O = 16.0 ) (7 marks/markah) (c) What is the volume (ml) of 0.150M H 2 SO 4 are required to react with 8.20g of sodium hydrogen carbonate? Berapakah isipadu (ml) 0.150M H 2 SO 4 diperlukan bagi bertindakbalas dengan 8.20g natrium hidrogen karbonat? END TAMAT

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