UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE PEPERIKSAAN IJAZAH SARJANA MUDA SAINS DENGAN PENDIDIKAN EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE WITH EDUCATION SESI AKADEMIK 2010/2011 : SEMESTER 1 ACADEMIC SESSION 2010/2011 : SEMESTER 1 SCES2230/SCEP2230 : KIMIA FIZIK II PHYSICAL CHEMISTRY II November/ Disember 2010 November/ December 2010 MASA : 2 jam TIME : 2 hours ARAHAN KEPADA CALON : INSTRUCTIONS TO CANDIDATES : Kertas soalan ini mengandungi Bahagian A, B dan C. This paper consists of Section A, B and C. Jawab soalan mengikut arahan yang diberikan dalam setiap bahagian. Questions should be answered according to the instructions given in each section. (Kertas soalan ini mengandungi 10 soalan dalam 11 halaman yang dicetak) (This question paper consists of 10 questions on 11 printed pages)
SCES2230/SCEP2230/02 Jawab SEMUA soalan dalam bahagian ini. Answer ALL questions in this section. BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) 1. Neils Bohr telah memodelkan atom hidrogen berdasarkan tiga anggapan sembarangan. Berikan anggapan-anggapan ini. Membandingkan dengan teori mekanik kuantum bagi atom, apakah yang silap berkenaan model ini?. Neil Bohr modelled the hydrogen atom based on three arbitrary assumptions. Give the assumptions. Comparing to the quantum mechanical theory of atom, what is wrong about the Bohr model? 2. Pertimbangkan satu sistem pengayun harmonik tiga dimensi (isotropik) Consider a system of three-dimensional (isotropic) harmonic oscillator. (8 markah/ marks) (a) (b) Dapatkan tenaga titik sifar bagi sistem ini. Find the zero-point energy for this system. Dapatkan degenerasi bagi paras tenaga yang mempunyai nilai (5/2)h bagi sistem ini. Find the degeneracy of the energy level having a value of (5/2)h for this system. [Petunjuk: Sesuatu adalah isotropik pada satu titik tertentu jika ianya dilihat sama dari semua arah apabila anda berada di titik tersebut.] [Hint: Something is isotropic at a particular point if it looks the same in all directions when you stand at that point.] (10 markah/ marks) 3. Dengan menggunakan perwakilan matriks bagi operator-operator spin, sahkan hubungan pertukartertiban di bawah. Using the matrix representation of the spin operators, verify the commutation relation below. [ ] = (8 markah/ marks)
SCES2230/SCEP2230/03 4. Pertimbangkan keadaan 3d +2 dan 3s bagi atom B 4+. Consider 3d +2 and 3s states of the B 4+ atom. (a) (b) (c) Terangkan secara ringkas menggunakan model vektor sama ada keduadua keadaan ini, 3d +2 dan 3s, merupakan fungsi eigen bagi,, dan? Briefly explain using the vector model whether these two states, 3d +2 and 3s, are eigenfunctions of,, and? Tanpa kehadiran satu medan magnet, dan tidak dipertimbangkan spin elektron, terangkan secara ringkas tenaga kedua-dua keadaan ini, 3d +2 dan 3s. In the absence of a magnetic field, and not including the spin of the electron, explain briefly the energy of these two states, 3d +2 and 3s. Dengan kehadiran satu medan magnet, dan tidak dipertimbangkan spin elektron, terangkan secara ringkas tenaga kedua-dua keadaan ini, 3d +2 dan 3s. In the presence of a magnetic field, and not including the spin of the electron, explain briefly the energy of these two states, 3d +2 and 3s. (14 markah/ marks) 5. Guna fungsi cubaan x(a x) untuk mengira keadaan tenaga terendah bagi zarah di dalam satu kotak satu dimensi dengan panjang 0 x a. Use trial function of the form x(a x) to calculate the ground-state energy of a particle in a one-dimensional box with length 0 x a. Jawab SEMUA soalan dalam bahagian ini. Answer ALL questions in this section. BAHAGIAN B (25 MARKAH) SECTION B (25 MARKS) 6. Terangkan secara ringkas salah satu (1) daripada yang berikut: Explain briefly one (1) of the following: (10 markah/ marks) (a) (b) Tindak balas berantai Chain reaction Penghampiran keadaan mantap Steady state approximation (4 markah/ marks)
SCES2230/SCEP2230/04 7. Kirakan halaju min, halaju min punca kuasa dua dan halaju paling mungkin untuk molekul oksigen pada 25 o C. Jika perlanggaran antara molekul oksigen berlaku pada 0.13 ns, dan diameter molekul O 2 ialah 370 x 10-12 m, kirakan ketumpatan molekul oksigen pada 25 o C. Calculate the mean speed, root mean square speed and most probable speed for oxygen molecules at 25 o C. If the collisions between oxygen molecules occur at 0.13 ns, given the diameter of O 2 molecule is 370 x 10-12 m, calculate the number density of oxygen molecule at 25 o C. (8 markah/ marks) 8. (a) Pemalar kadar tindak balas yang ditentukan secara eksperimen untuk tindak balas di antara logam alkali dan halida adalah berkali ganda lebih besar daripada pemalar kadar yang dikira dengan teori perlanggaran mudah. Terangkan pemerhatian ini. The experimentally measured rate constants for the reactions between the alkali metals and the halides were found to be several orders of magnitude larger than the rate constant values calculated using the simple collision theory. Explain this observation. (8 markah/ marks) (b) Kirakan keratan rentas untuk tindak balas antara K dengan Br 2. Diberi tenaga pengionan K ialah 420 kj mol -1, dan afiniti elektron Br 2 ialah 250 kj mol -1. Cas elektron, e = 1.602 x 10-19 C, dan ketelusan vakum, ε 0 = 8.854 x 10-12 J -1 C 2 m -1. Calculate the cross section for the reaction between K and Br 2. The ionization energy of K is 420 kj mol -1, and the electron affinity of Br 2 is 250 kj mol -1. Electronic charge, e = 1.602 x 10-19 C, and the permittivity of vacuum, ε 0 = 8.854 x 10-12 J -1 C 2 m -1. (5 markah/ marks)
SCES2230/SCEP2230/05 BAHAGIAN C (25 MARKAH) SECTION C (25 MARKS) Jawab SATU (1) soalan sahaja dalam bahagian ini. Answer ONE (1) question only in this section. 9. (a) Apa yang anda faham dengan sebutan berikut: What do you understand by the following terms: (i) (ii) pembedaan penuh bagi fungsi keadaan yang bergantung total differential of a dependent state function pembolehubah komposisi composition variable (iii) tekanan dalaman internal pressure (10 markah/ marks) (b) Oksigen mematuhi persamaan berikut pada tekanan sederhana Oxygen obeys the following equation at moderate pressures dimana b = 0.0211 dm 3 mol -1. where b = 0.0211 dm 3 mol -1. P(V m b) = RT (i) (ii) hitung fugasiti gas pada 25 o C dan tekanan 1 bar. calculate the fugacity of the gas at 25 o C and 1 bar pressure. hitung tekanan pada mana fugasiti bersamaan 1 bar. calculate the pressure at which the fugacity equals 1 bar. Pembayang: ambil kembangan e -x = 1. Hint: take expansion of e -x = 1. (8 markah/ marks)
SCES2230/SCEP2230/06 (c) Diberi pekali pengembangan 1.82 x 10-4 K -1 dan kemampatan isoterma 3.87 x 10-5 atm -1. Given that the expansion coefficient 1.82 x 10-4 K -1 and the isothermal compressibility 3.87 x 10-5 atm -1. (i) tentukan sebutan dalam sebutan dan, dan determine the term for in terms of and, and (ii) nilaikan sebutan evaluate the term (7 markah/ marks) 10. (a) Terangkan dalam konteks termodinamik sebutan berikut Explain in thermodynamics context the following terms (i) (ii) kespontanan spontaneity keterbalikan reversibility (iii) keupayaan kimia chemical potential (10 markah/ marks) (b) Suatu larutan etanol-air dengan 40% etanol secara jisim mempunyai ketumpatan 0.945 g ml -1 pada 25 o C. Hitung pecahan mol, kepekatan dan kemolalan etanol. (BM etanol = 46.048 g mol -1, air = 18.016 g mol -1 ). An ethanol-water solution which is 40% ethanol by mass has a density of 0.945 g ml -1 at 25 o C. Compute the mole fraction, concentration and molality of ethanol. (MW of ethanol = 46.048 g mol -1, water = 18.016 g mol -1 ). (c) markah/ marks)
SCES2230/SCEP2230/07 (c) (i) Hitung tekanan yang diperlukan untuk melebur air pada 10 o C jika isipadu molar air cecair ialah 18.01 ml dan isipadu molar ais ialah 19.64 ml. S m untuk proses ialah +22.04 J K -1 dan andaikan nilai nilai ini adalah tetap dengan suhu. 1 L bar = 100 J. Calculate the pressure necessary to melt water at 10 o C, if the molar volume of liquid water is 18.01 ml and the molar volume of ice is 19.64 ml. S m for the process is +22.04 J K -1 and assume these values remain constant with temperature. 1 L bar = 100 J. (ii) Bermula dengan dh = TdS + VdP, terbitkan ungkapan Starting from dh = TdS + VdP, derive the expression dimana JT = dan C P =. where JT = and C P =. (iii) Tentukan nilai JT untuk gas unggul dengan mengandaikan kuantiti molar. Determine the value of JT for an ideal gas, assuming molar quantities. (9 markah/ marks)
FUNGSI-FUNGSI MATEMATIK DAN FORMLA-FORMULA. MATHEMATICAL FUNCTIONS AND FORMULAS. SCES2230/SCEP2230/08
SCES2230/SCEP2230/09
SCES2230/SCEP2230/10
LAMPIRAN BARU (PEMBETULAN) SCES2230/SCEP2230/11 /2 TAMAT END