/8 b) An experiment is conducted and the final temperature reached is 27.90 o C. Propose a reason the temperature of 28.88 o C was not reached in grammatically correct English sentences. /4
CHEM 105 E2 F18 9a) You are holding two balloons that have been filled for a long enough period of time that thermal equilibrium has been reached. The first balloon contains a mixture of N 2 (g) and O 2 (g). If the total pressure in the balloon is 0.986 atm, what is the atmospheric pressure in the room you are standing in (assume elasticity of the balloon can be ignored). Explain your response. /4 b) In each part below, circle the correct symbol. If there is not enough information to determine the correct relationship, do not circle any of the symbols. Below each part, explain your response in one sentence or less. i) The volume of N 2 is > < = the volume of O 2 Explanation: ii) The pressure of N 2 is > < = the pressure of O 2 Explanation: iii) The kinetic energy of N 2 is > < = the kinetic energy of O 2 Explanation: iv) The average speed of N 2 is > < = The average speed of O 2 Explanation: /12 c) The second balloon contains N 2 (g) and an unknown Nobel gas. The balloon contains 2.75 g of N 2 (g) with a partial pressure of 0.753 atm. If the total mass of gas within the balloon is 4.00 g, identify the unknown gas by finding the molar mass? Hint: you are holding the balloon in the same room as the balloon in part (a). /6
CHEM 105 E2 F18 10) Determine the enthalpy of combustion of methane using the given structures and bond enthalpies: CH 4 (g) +2O 2 (g) Æ CO 2 (g)+2H 2 O(g) O=O 495 kJ/mol C-O 358 kJ/mol O-H 464 kJ/mol O-O 146 kJ/mol C=O 745 kJ/mol H-H 432 kJ/mol C-H 413 kJ/mol C=C 614 kJ/mol /6 b) The enthalpy of formation of CH 4 ( g ) is -74.85 kJ/mol, of H 2 O( g ) is -285.82 kJ/mol and of CO 2 ( g ) is -393.52 kJ/mol. Determine the enthalpy of the reaction in 9(a) using enthalpies of formation. /6 c) State one possible reason why there may be a difference between the values determined in 9(a) and 9(b). Explain why your answer may be true.
- Fall '08