PEPERIKSAAN IJAZAH SARJANA MUDA SAINS
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE
SESI AKADEMIK 2016/2017 : SEMESTER II ACADEMIC SESSION 2016/2017 : SEMESTER II
SCES1230 : KIMIA FIZIK I
PHYSICAL CHEMISTRY I
Jun 2017 MASA: 2 jam
June 2017 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 di dalam setiap bahagian.
Question should be answered according to the instructions given in each section.
(Kertas soalan ini mengandungi 6 soalan dalam 7 halaman yang bercetak) (This question paper consists of 6 questions on 7 printed pages)
2/7 BAHAGIAN A (50 MARKAH)
SECTION A (50 MARKS)
Jawab SEMUA soalan.
Answer ALL questions.
1. (a) Bincangkan proses sesuhu, proses adiabatik, proses isokorik dan proses setekanan.
Discuss the isothermal process, adiabatic process, isochoric process and isobaric process.
(8 markah/ marks)
(b) Gas ideal menjalani pengembangan sesuhu pada 77 ºC meningkatkan jumlah isipadunya dari 1;3 ke 3;4 L. Perubahan entropi gas adalah 24 J/K. Berapa mol gas yang hadir?
An ideal gas undergoes an isothermal expansion at 77 ºC increasing its volume from 1.3 to 3.4 L. The entropy change of the gas is 24 J/K. How many moles of gas are present?
(4 markah/ marks)
(c) Berapa kuantiti haba yang diperlukan untuk mencair 500 g ais dan memanas air kepada wap pada 100 oC?
(Haba pelakuran ais = 333 J/g, Haba tentu air = 4.2 J/g oC, Haba pengewapan = 2260 J/g)
What quantity of heat is required to melt 500 g of ice and heat the water to steam at 100 oC?
(Heat of fusion of ice = 333 J/g, Specific heat of water = 4.2 J/g oC, Heat of vaporization = 2260 J/g)
(5 markah/ marks)
(d) Lakar kalorimeter bom dan terangkan bagaimana haba tindakbalas pembakaran boleh ditentukan.
Draw a Bomb calorimeter and show how the heat of a combustion reaction can be determined.
(8 markah/ marks)
3/7 2. (a) Satu sampel bifenil (C6H5)2 seberat 0.526 g telah dinyalakan dalam
kalorimeter bom pada suhu awalan pada 25 °C, menghasilkan kenaikan suhu 1.91 K. Dalam eksperimen penentukuran yang berasingan, sampel asid benzoik C6H5COOH seberat 0.825 g dinyalakan di bawah keadaan yang sama dan menghasilkan kenaikan suhu sebanyak 1.94 K. Untuk asid benzoik, haba pembakaran pada tekanan malar diperoleh sebagai 3226 kJ mol–1 (iaitu, ΔU = -3226 kJ mol–1). Guna maklumat ini untuk menentukan entalpi piawai pembakaran bifenil.
A sample of biphenyl (C6H5)2 weighing 0.526 g was ignited in a bomb calorimeter initially at 25°C, producing a temperature rise of 1.91 K. In a separate calibration experiment, a sample of benzoic acid C6H5COOH weighing 0.825 g was ignited under identical conditions and produced a temperature rise of 1.94 K. For benzoic acid, the heat of combustion at constant pressure is known to be 3226 kJ mol–1 (that is, ΔU = –3226 kJ mol–
1.) Using this information, determine the standard enthalpy of combustion of biphenyl.
(7 markah/ marks)
(b) Tulis persamaan seimbang dan lakar gambarajah entalpi anggaran untuk setiap yang berikut:
(i) Pembakaran satu mol metana dalam oksigen.
(ii) Pembekuan air.
Write a balanced equation and draw an approximate enthalpy diagram for each of the following:
(i) The combustion of one mole of methane in oxygen (ii) The freezing of liquid water.
(8 markah/ marks)
(c) Seorang pesakit telah mengambil sejumlah 1 mol glukosa (dalam minuman) selama dua hari. Berapa banyak tenaga disediakan untuk mengekalkan aktiviti otot dan saraf daripada pembakaran glukosa pada 37 oC (suhu badan pesakit)?
Diberi ∆Hocomb = -2808 kJ mol-1 dan ∆S = 182.4 JK-1mol-1.
A patient has taken a total of 1 mol glucose (in drink) over two days. How much energy is available for sustaining muscular and nervous activities from the combustion of glucose at 37 oC (the body temperature of the patient)?
Given ∆Hocomb = -2808 kJ mol-1 and ∆S = 182.4 JK-1mol-1.
(5 markah/ marks)
4/7 (d) Apabila petrol terbakar dalam enjin kereta, haba yang dibebaskan
menyebabkan produk CO2 dan H2O mengembang yang mana seterusnya menolak omboh. Haba yang berlebihan dikeluarkan oleh sistem penyejuk kereta. Jika pengembangan gas melakukan 451 J kerja pada piston dan sistem kehilangan 325 J ke persekitaran sebagai haba, kira perubahan tenaga (ΔE).
When gasoline burns in a car engine, the heat released causes the products CO2 and H2O to expand which pushes the piston onward. Excess heat is removed by the car’s cooling system. If the expanding gases do 451 J of work on the pistons and the system loses 325 J to the surroundings as heat, calculate the change in energy (∆E).
(5 markah/ marks)
BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS)
Jawab SEMUA soalan.
Answer ALL questions.
3. (a) Bezakan di antara sel voltaik dan sel elektrolitik.
Distinguish between a voltaic cell and an electrolytic cell.
(6 markah/ marks)
(b) Seimbangkan tindakbalas redoks berikut dan kenalpasti agen pengoksidaan dan penurunan.
Balance the following redox reactions and identify oxidizing and reducing agents.
NO3- (ak) + H+ (ak) + Cu (p) Cu2+ (ak) + NO (g) + H2O (c) NO3- (aq) + H+ (aq) + Cu (s) Cu2+ (aq) + NO (g) + H2O (l)
(5 markah/ marks)
4. (a) Kira keupayaan sel piawai, 𝐸𝑐𝑒𝑙𝑙 dan tenaga bebas Gibbs piawai, G
bagi tindak balas berikut.
Calculate the standard cell potential, 𝐸𝑐𝑒𝑙𝑙 and the standard Gibbs free energy, G of the following reaction.
2Au (p) + 3Ca2+ (ak) 2Au3+ (ak) + 3Ca (p) 2Au (s) + 3Ca2+ (aq) 2Au3+ (aq) + 3Ca (s)
Diberi Ered Au3+/Au = 1.50 V and Ered Ca2+/Ca = -2.87 V.
Given 𝐸𝑟𝑒𝑑 Au3+/Au = 1.50 V and 𝐸𝑟𝑒𝑑 Ca2+/Ca = -2.87 V.
(10 markah/ marks)
5/7 (b) Terangkan sekurang-kurangnya dua (2) tujuan penggunaan titian
garam di dalam sel elektrokimia.
Explain at least two (2) purposes of using salt bridge in an electrochemical cell.
(2 markah/ marks)
(c) Ramal produk yang terhasil daripada elektrolisis 1.0 M larutan AlBr3. Diberi:
2H2O (c) + 2e− H2 (g) + 2OH− (ak) 𝐸𝑟𝑒𝑑 = -0.83 V O2 (g) + 4H+ (ak) 4e− 2H2O (c) 𝐸𝑟𝑒𝑑 = 1.23 V Predict the products obtained from electrolysis of 1.0 M AlBr3 solution.
Given:
2H2O (l) + 2e− H2 (g) + 2OH− (aq) 𝐸𝑟𝑒𝑑 = -0.83 V O2 (g) + 4H+ (aq) 4e− 2H2O (l) 𝐸𝑟𝑒𝑑 = 1.23 V
(8 markah/ marks)
5. (a) Bezakan antara pemangkin homogen dan pemangkin heterogen.
Distinguish between a homogeneous catalyst and a heterogeneous catalyst.
(4 markah/ marks)
(b) Terangkan bagaimana suatu mangkin dapat mempercepatkan kadar tindakbalas.
Explain how a catalyst accelerates the rate of reaction.
(3 markah/ marks)
6. (a) Penguraian nitrogen dioksida kepada nitrogen dan oksigen adalah tertib kedua dengan pemalar kadar 15.5 M-1s-1. Jika kepekatan awal nitrogen dioksida adalah 0.0500 M, kira separuh hayat tindakbalas tersebut.
The decomposition of nitrogen dioxide to nitrogen and oxygen is second order with a rate constant of 15.5 M-1s-1. If the initial concentration of nitrogen dioxide is 0.0500 M, calculate the half-life of the reaction.
(3 markah/ marks)
(b) Pemalar kadar bagi penguraian fasa gas hidrogen iodida, 2 HI (g) H2 (g) + I2 (g), disenaraikan dalam jadual berikut:
The rate constants for the gas phase decomposition of hydrogen iodide, 2 HI (g) H2 (g) + I2 (g), are listed in the following table:
6/7 Suhu/
Temperature, ᵒC k, M-1 s-1
283 3.52 10-7
508 3.95 10-2
Hitung tenaga pengaktifan, Ea (dalam kJmol-1) untuk tindakbalas tersebut. [Pemalar gas, R = 8.314 JK-1mol-1]
Calculate the activation energy, Ea (in kJmol-1) for the reaction.
[Gas constant, R = 8.314 JK-1mol-1]
(6 markah/ marks)
(c) Mekanisma berikut telah dicadangkan untuk tindakbalas hidrogen dan iodin monoklorida:
Langkah 1: H2 (g) + ICl (g) HI (g) + HCl (g) langkah perlahan Langkah 2: HI (g) + ICl (g) I2 (g) + HCl (g) langkah cepat The following mechanism has been proposed for the reaction of hydrogen and iodine monochloride:
Step 1 : H2 (g) + ICl (g) HI (g) + HCl (g) slow step Step 2 : HI (g) + ICl (g) I2 (g) + HCl (g) fast step
(i) Kenal pasti intermediate bagi tindakbalas.
Identify the intermediate for the reaction.
(ii) Tentukan molekulariti untuk setiap langkah.
Determine the molecularity of each step.
(iii) Beri persamaan seimbang bagi tindakbalas keseluruhan.
Give the balanced equation for the overall reaction.
(3 markah/ marks)
7/7 TAMAT
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