SULIT JIK102 Take Home Test 2 2019/2020 Academic Session July 2020 JIK102 – General Chemistry II (Kimia Am II) Duration : 1 hour 30 minutes (Masa : 1 jam 30 minit) Instructions : Answer ALL questions. Answer the questions in English. Your answers must be HANDWRITTEN using PEN. Do not rewrite your questions on your answer sheets. All answers must be SCAN and email to anistasnim@usm.my -1- SULIT 1. JIK102 (a). Benzene has a melting point of 5.53 oC and a boiling point of 80.09 oC at atmospheric pressure. Its density is 0.8787 g cm-3 when liquid and 0.899 g cm-3 when solid. It has Tc = 289.01 oC, Pc = 48.34 atm, Tt = 5.52 oC and Pt = 0.0473 atm. Sketch a phase diagram. Starting from a point at 200 K and 66.5 atm, trace the following path when: (i). T increased to 585 K while keeping P constant. (ii). P decreased to 38.5 atm while keeping T constant. (iii). T decreased to 278.6 K while keeping P constant. (iv). P decreased to 0.0025 atm while keeping T constant. Identify the starting and final phases of benzene. [15 marks] (b). A small cylinder of helium gas used with a volume of 2.30 L and a pressure of 13800 kPa at 25 oC was used to fill balloons. Show the number of balloons that can be filled when each of the balloons has a volume of 1.5 L and a pressure of 1.25 atm at 25 oC. [5 marks] 2. (a). For the reaction of H2(g) + Br2(g) 2 HBr(g), the values of Kp and ΔHo at 1000 K are 2.1 x 106 and -107.7 kJ, respectively. (i). Calculate the partial pressures of H2, Br2 and HBr at equilibrium when 0.974 mol of Br2 is added to a 1.00 L reaction vessel that contains 1.22 mol of H2 gas at 1000 K. SULIT JIK102 (ii). For the equilibrium in part (i)., each of the following changes will increase the equilibrium partial pressure of HBr. [A]. Adding 0.10 mol of H2 [B]. Adding 0.10 mol of Br2 [C]. Decreasing the temperature to 700 K Choose the change that will cause the greatest increase in pressure of HBr. Explain your choice. [16 marks] (b). The concentration of H3O+ ions in a sample juice is 2.5 x 10-3 M. Calculate the concentration of OH- ions. Identify the acid-base properties of the solution. [4 marks] SULIT JIK102 APPENDIX Table 1 Specific Heat Values of Some Common Substances Substance Specific Heat (Jg-1 oC-1) Al(s) 0.900 Au(s) 0.129 C(graphite) 0.720 C(diamond) 0.502 Cu(s) 0.385 Fe(s) 0.444 Hg(l) 0.139 H2O(l) 4.184 C2H5OH(l) -ethanol 2.46 Avogadro’s number = 6.022 x 1023 SULIT JIK102 Gas Constant, R in various units R = 8.314 J K-1 mol-1 R = 8.314 Pa m3 K-1 mol-1 R = 8.314 x 10-2 L bar K-1 mol-1 R = 0.0821 atm L K-1 mol-1 R = 62.36 L Torr K-1 mol-1 R = 1.987 cal mol-1 k-1 Unit of Pressure and Conversion Factors Unit of Pressure Symbol Numerical Value Pascal Pa 1 Nm-2 = 1 kgm-1s-2 Atmosphere atm 1 atm = 101325 Pa Bar Bar 1 bar = 105 Pa Torr or millimeters of Hg Torr 1 Torr = 101325/760 = 133.32 Pa 1 Cal = 4.184 J F = 96,485 C/mol Cp = 4.19 Jg-1K-1 K= 1.38 x 10-23 J/K Types of Work Types of Work Variables Equation for Work Conventional Units Volume Expansion Pressure (P), Volume (V) w= -∫PexternaldV Pam3 = J Stretching Tension (γ), length (l) w= -∫γdl Nm = J SULIT JIK102 - oooOooo -