(Kertas soalan ini mengandungi 6 soalan dalam 6 halaman yang dicetak) (This question paper consists of 6 questions on 6 printed pages)

Transcription

1 UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE SESI AKADEMIK 2016/2017 : SEMESTER 1 ACADEMIC SESSION 2016/2017 : SEMESTER 1 SCES2338/SIC2013 : KIMIA KEADAAN PEPEJAL SOLID STATE CHEMISTRY Dis 2016/Jan 2017 Dec 2016/Jan 2017 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 6 soalan dalam 6 halaman yang dicetak) (This question paper consists of 6 questions on 6 printed pages)

2 BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 1. (a) Bincangkan bagaimana anda mencirikan pepejal kristal atas dasar sifatkuasa mengikat antara zarah konstituen. Discuss on how do you characterize the crystalline solids on the basis of nature of binding forces between the constituent particles? (b) Struktur kubik berpusat padu (BCC), kubik berpusat muka (FCC) dan heksagonal tertutup padat (HCP) mengandungi ruang celahan tetrahedron. Lukis sel unit dan ruang tetrahedron bagi kekisi BCC, FCC dan HCP tersebut. The BCC, FCC and HCP structures contain tetrahedral interstitial holes as well as octahedral ones. Draw unit cell and tetrahedral hole of the body centered cubic (BCC), face centered cubic (FCC) and hexagonal closed packed (HCP) lattices. (15 markah/marks) 2. (a) Struktur ringkas pepejal ionik terdiri daripada susunan anion (atau kadang-kala kation) dengan kedudukan sfera berada pada kekisi kubik berpusat muka (FCC) atau heksagonal tertutup padat (HCP) dan kation berada di sebahagian atau keseluruhan ruang oktahedra dan tetrahedral dalam kekisi tersebut. Terangkan perbezaan susunan anion dan kation dalam struktur garam batu, fluorit dan wurtzit. The simple structures of ionic solids come from arrangement of the anions (though sometimes the cations) in the positions of the spheres in the face centered cubic (FCC) or hexagonal closed packed (HCP) lattices and the cations go into some or all of the octahedral and tetrahedral holes within the lattices. Describe the different in arrangement of anions and cations in rock salt, fluorite and wurtzite structures. (b) Sel unit aluminium (M = 27 g/mol) adalah kiub dengan panjang tepi 4.05 Å. Ketumpatan aluminium tersebut adalah 2.70 g/cm 3. Tentukan struktur kristal aluminium. The unit cell of aluminium (M = 27 g/mol) is a cube with edge length 4.05 Å. The density of aluminium is 2.70 g/cm 3. Determine the structure of aluminium crystals. (15 markah/marks) 2/6

3 3. (a) Tentukan indeks Miller bagi planar-planar yang ditunjukkan pada sel unit berikut. Determine the Miller indices for the planes shown in the following unit cell. (b) Beri sebab mengapa planar (-1-1 1) dan ( ) tidak termasuk dalam kumpulan {111}. Give reason on why (-1-1 1) and ( ) planes are not included in the complete {111} family. (10 markah/marks) 4. Pertimbangkan corak XRD aluminium berikut yang telah didapati melalui radiasi CuKα. Indekskan corak ini dan tentukan planar Bravais dan parameter - parameter planar tersebut. Jadual dibawah menunjukkan nilai 2θ bagi kesemua puncak. Consider the following XRD pattern for aluminium, which was collected using CuKα radiation. Index this pattern, determine the Bravais lattice and lattice parameters. Table below shows the 2θ for all peaks. 3/6

4 Nombor puncak/ Peak Number 2θ SCES2338/SIC2013 (10 markah/marks) 4/6

5 BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 5. (a) Apakah sebatian bukan-stoikiometrik? Terangkan bagaimana ia boleh disediakan. What are non-stoichiometric compounds? Explain how they can be prepared. (10 markah/marks) (b) Apakah kriteria yang perlu dipatuhi untuk membentuk suatu larutan pepejal celahan. Terangkan dengan bantuan gambarajah mengapa karbon, C, boleh larut dalam kubik berpusat muka besi (γ-fe) tetapi tidak dalam kubik berpusat jasad besi (α-fe). What are the criteria that must be met to form an interstitial solid solution. Explain with diagram why carbon, C, is soluble in face-centered cubic iron (γ-fe) but not in the body-centered cubic iron (α-fe). (7 markah/marks) (c) Jawab soalan berikut berdasarkan gambarajah fasa eutektik bagi sistem Pb/Sn yang diberikan di bawah. Answer the following questions based on the eutectic phase diagram of the Pb/Sn system given below. 5/6

6 (i) (ii) Kenalpasti fasa, komposisi dan jumlah relatif bagi 25 wt% Sn pada suhu 195 C? Identify the phases, their compositions and relative amounts for 25 wt% Sn at a temperature of 195 C? Nyatakan bilangan komponen (C), darjah kebebasan (F) dan bilangan fasa (P) yang wujud pada suhu 183 C, 60 wt% Sn. State the number of components (C), the degree of freedom (F) and the number of phases (P) exist at the temperature of 183 C, 60 wt% Sn. (8 markah/marks) 6. (a) Sifat elektrikal bagi bahan pepejal adalah dipengaruhi oleh struktur jalur elektronik. Jelaskan jalur elektronik dalam logam, penebat dan semikonduktor. The electrical properties of a solid material are a consequence of its electronic band structure. Describe the electronic bands in metals, insulators and semiconductors. (12 markah/marks) (b) Terangkan apa itu kepiezoelektrikan? Beri contoh bahan yang menunjukkan kepiezoelektrikan dan berikan beberapa contoh pengunaan di mana kepiezoelektrikan digunakan. Explain what is piezoelectricity? Give an example for material that shows piezoelectricity and provide a few applications in which piezoelectricity is used. (5 markah/marks) (c) Kuantum dots menunjukkan sifat optik yang unik. Bilangan atom dalam kuantum dots menentukan saiz, dan saiz pula menentukan warna cahaya yang dipancarkan. Jelaskan. Quantum dots display unique optical properties. The number of atoms in the quantum dot determines their size, and the size of the quantum dot determines the colour of light emitted. Explain. (8 markah/marks) TAMAT END 6/6