Question

[2] (a) Consider the reaction of methane, CH4, burning in the presence of oxygen at constant pressure. Given the following equation, how much heat could be obtained by the combustion of 15.0 grams methane (CH4)? (Supporting information: C = 12, H = 1,0 - 16) (CSLO 3, Application) Marks CH (8) + 20 (8)4C0,4g)+ 2H 2017), NH" = -890.3 k! [2] (b) A sample of sulfur dioxide occupies a volume of 652 mL at 40° C and 720 mm Hg. What volume will the sulfur dioxide occupy at 0° C and 760 mm of Hg? (CSLO 3, Application) Marks = 1 (3) (a) Why is a Chemistry considered a Science for the Twenty-First Century? (CSLO 1, Comprehension) Marks = 1 [3] (b) What does the electrolyte and non-electrolyte describe? (CSLO 1, Comprehension) Marks = 1 [4] (a) Describe the effect of pressure and temperature on the rate of a chemical reaction? (CSLO 2, Comprehension) Marks = 1 [4](b) Describe the chemical equilibrium constant (Key) when a mixture of H2 and N2 is allowed to react in presence of Fe catalyst? (CSLO 2, Comprehension) Marks = 1 [5] (a) Describe the neutralization and displacement reactions with suitable example? (CSLO 1, Comprehension) Marks = 1 [5] (b) Discuss the acid-base reactions with two examples? (CSLO 2, Comprehension) Marks = 1

Answer 1

Solution [2] as Molecules Mass of methane : CH4 = (12x1 + 1x4) = 16 goo/mol Therefore, 16 gm c Hy = 1 mole methane 15 gm Cty = 4/5x15 » = 0.9375 mole methane. The given following combustion reaction - Chala) + 202(8) + CO2(8) + 2H20 (1); AH = -890.3 KJ Use the enthalpy change of combustion to find the heat given off when 0.9375 moles of Cty undergo Combustion- = (0.9375 moles Chu) x6290.3kJ) 1 mole chy = - 834.66 KJ. Hence, 834.66 kJ heat could be obtained by the Combustion of 15.0 grams Chy. [2] (6) Formula: P Pi = 720 mmHg v, = 652 mi T, = 40°c = (40+273) = 313 K P₂ = 760 mm Hg ₂ = ? T2 = 0°c = 273 . The 7600matgex 720 mattg x 652m. 313 K 2734 760 mmit 720 X 652 X 273 2 m 313x760 = 538.75 mi

Hence, volume of sulfur dioxide is 538.75 m. [3] (a) chemists creats new molecules, new materials, uncover new Phenomena, and create new Problems that naise new questions. A organic chemishy synthesis new organic molecules to use day-to-day life and many other nesonce to Considered chemistry is a science. salts or molecules that fully ionize in a solutions neadily [8] 6) • Electrolytes are solution. As a result, electrolyte Conduct electricity. Example: Nacl, kel, Mtuce, Naolt etc. Non-electroly do not dissociate into ions in solution, and do not conduct electricity. Example: C6H12O6, CH₂OH, CHS OH etc. [4] (a) when in a given chemical reaction, the pressure is increase, the molecules have loss space in which they can move. That greater density of molecules increases the number of Collisions. when you decrease the pressure, molecules do not hit each other as often and the rate of reaction decreases. 0 when it is temperature increases, the neactants have more kinetic energy so the frequency of effective Collision increases, resulting in a faster rate of Chemical reaction. (4] (6) Inon is a cheap Catalyst used in the Haber Process (N2 73H2 FC 2NH3). it increase the nate of reaction in chemical Processes. But Catalysts do not effect on the value of an equilibrium Constant.