Chemistry 1031 Fall 2016 Exam 2 PDF

NAME: _________________________________ TEMPLE ID #:_____________________________ RECITATION SESSION: ___________________ RECITATION TA: _________________________ CHEMISTRY 1031 – Fall 2016, EXAM II Instructions: The multiple choice questions (1 t...

NAME: _________________________________ TEMPLE ID #:_____________________________ RECITATION SESSION: ___________________ RECITATION TA: _________________________ CHEMISTRY 1031 – Fall 2016, EXAM II Instructions: The multiple choice questions (1 through 20) add up to 80 points (4 points each). The problems (A, B and C) are worth 10 points each and will be graded separately. The total available points are 110, which means there are 6 points of extra credit available.  On the exam packet: 1. Write your name, ID #, Recitation Sessions and TA name at the top of this page; 2. Use pages 3 and 4 as scrap paper; 3. Write your answer on the blank lines provided next to each question, THEN transfer your answers to the scantron sheet. You may erase on this packet, not on the scantron sheet; 4. Use the space provided for the problems as scrap paper. This will NOT be graded.  On the scantron sheet: 1. Print your TU ID in the boxes provided and fill in the bubbles below. Start with 9 in the left hand box. The box on the far right should be left empty. 2. Do not write in your phone number. 3. Print your name in the boxes provided, leave a space between your last name and your first name, and fill in the bubbles below. 4. Leave CODE, TEST FORM, and SUBJ SCORE blank. 5. Fill in the bubbles for each question on the front of the Scantron sheet. No answer is a wrong answer; two bubbles for the same answer is also a wrong answer. 6. Write down neatly detailed work for the open-ended problems, on the back of the Scantron sheet. No credit if no work is shown. No graphing or memory accessible calculators are allowed at your examination desk. No cell phones or PDAs are allowed on your persons. Violation of these department rules will be brought to the attention of the Chemistry Department Chairman, the Dean and the Provost, and may result in significant disciplinary action for violation of university standards of academic integrity. Multiple Choice Questions: ________________ / 80 Problem A: _________________ / 10 Problem B: ________________ / 10 Problem C: ________________ / 10 Total Score: ______________________ / 100 1 2 Open-ended problems. Do not get scared. You solved dozens of problems for practice; these are only three more. Analyze what is in the beaker and set up the problem. Partial credit will be given for problem set up correctly, even though the math may not be correct. I am interested in seeing if your thought process goes in the right direction and where you are instead getting stuck. Please write up the answers neatly on the back of the Scantron sheet. Problem A. In an experiment, 4 moles of oxygen gas are consumed during the combustion of an unknown amount of C6H12O6. What pressure of carbon dioxide would result from this reaction at 25.0 C if captured in a 250 L vessel? Problem B. A block of hot iron (Cs,iron = 0.444 J / g C) of unknown mass is dropped into an insulated cup filled with 100 mL vegetable oil (density of oil, 0.93 g/mL; Cs,oil = 2.00 J / g C). If the temperature of the oil increases 60 C, and the temperature of the iron decreases by 60 C, what is the mass of the hot iron block? Assume the iron and oil are thermally isolated from everything else. Problem C. The H of reaction for the combustion of glucose (C6H12O6) and of saccharose (C12H22O11) are respectively - 2805 kJ and -5644 kJ. Calculate the enthalpy for the reaction of hydrolysis of saccharose into two molecules of glucose: C12H22O11 (s) + H2O (l)  2C6H12O6 (s). 3 4  PART I: Gasses. 1. ___ A balloon contains 1.30 L of helium at standard temperature and pressure (STP). At 3 atm pressure, what is the volume of the balloon (assuming no change in temperature)? A) 0.300 L B) 3.90 L C) 329 L D) 0.433 L E) None of the above 2. ___ The reaction of Problem A (see previous page) is best described as A) an endothermic reaction B) an exothermic reaction C) a thermal reaction D) a heat-absorbing reaction E) More info is needed to answer 3. ___ Which gas is the least dense at 300 K and 1.2 atm? A) oxygen (O2) B) helium (He) C) nitrogen (N2) D) xenon (Xe) E) More info is needed to answer 4. ___ Which of the gas molecules has the highest rate of effusion (assuming the same conditions of temperature and pressure)? A) 14N2 B) 15N2 C) 16O2 D) 18O2 E) More info is needed to answer Consider the following distribution graphs to answer questions 5-7. A A B A B C B D C A A B A A 5. ___ The graph on the left shows the M-B distribution for the lightest four noble gasses. Which (a, b, c or d) corresponds to the one for neon? 6. ___ To which curve will the one for fluorine gas (F2) most look similar? (a, b, c or d) 7. ___ The graph on the right shows instead the M-B distribution for samples of N2 gas at different temperatures. Which curve corresponds to the hottest sample of gas? A) A B) B C) C D) More info is needed E) None of the above 5   n2  8.___ In the van der Waals’s equation:  P  a V - nb   nRT , the constant…  V 2  A. a takes into account the increase in pressure due to the size of the gas particles B. b takes into account the decrease in volume due to the attractions between the gas particles C. b takes into account the increase in volume due to the size of the gas particles D. a takes into account the increase in pressure due to the attractions between the gas particles 9. ___ The graph on the right shows the real volume of four gases when compared to that of an ideal gas, as function of the pressure. Three of the four gases have a real volume smaller than the ideal one, at low pressure. Hydrogen doesn’t. Why? A. Hydrogen molecules have stronger intermolecular forces B. Hydrogen molecules are the smallest in volume C. Hydrogen molecules are the lightest by mass D. Hydrogen molecules are at a higher temperature than the others PART 2: work and heat 10. ___ Which of these values is a specific heat capacity? A) 2 J / K B) 3.2 J / mol K C) 15.3 J / kg K D) 32 K / J g E) More info needed 11. ___ Dry ice (solid carbon dioxide, stored at -78 C) is placed in a balloon. The balloon is sealed, and stored on a lab bench at room temperature. As the dry ice warms it becomes gaseous carbon dioxide, which expands the balloon. If the balloon is the system (including the gas and carbon dioxide inside of it), the signs of q and w are A) q>0, w0, w>0 D) q