Sample Exam CHM 1110 F201 Use the following information for questions 6-9. Ar gas P = 3.65 atm V = 3.00 L T = 298 K Kr gas P = 5.25 atm nKr = 0.537 mol T = 298 K empty V = 5.00 L 6. What is the volume of the bulb containing Kr? a) 4.66 L b) 0.21 L c) 2.50 L d) 239 L 7. What are the ΧKr and ΧAr in the vessel when all of the valves are open? (4 points for work, 2 points for each answer) 8. What is the PAr when all the valves are open? (6 points for work, 2 points for answer) 9. If this entire system were shrunk to a total volume of 1.0x10-10 mL, briefly explain why the ideal gas law would no longer apply? (4 points) Use the following information for questions 14-17. An electron in n = 5 of H emits a photon and moves to n = 3. 14. What is the wavelength of light (in nm) that is emitted? (7 points for work, 3 points for answer) 15. In which part of the electromagnetic spectrum does this photon emit? a) visible b) infrared c) ultra-violet d) x-ray 16. If the electron (m = 9.11x10-31kg) moving between energy levels had a wavelength of 1.62 Å of what is its velocity? (4 points for work, 2 points for answer) (1 Å = 1x10-10m) 17. Which of the following statements is true regarding Bohr’s model of the H-atom? a) The energy levels of H are of specific values. b) All light will cause electrons to move energy levels given enough time. c) The energy emitted by the H-atom is continuous. d) Bohr’s model can be extrapolated and works for all atoms. Use the following information for questions 18-21. Os 76 18. a) What is the electron configuration for Os? (4 points) 19. What are the four quantum numbers of the last electron placed into Os by the Aufbau principle? (4 points) n= l= ml (all possible values) = ms (all possible values) = 20. Draw one of the possible orbitals that corresponds to where the last electron of Os is located. Make sure you indicate which orbital you are drawing and label axes. (3 points) 21. How many unpaired electrons does Os have? a) 1 b) 6 c) 2 d) 4 21. A bottle of KOH was found in the laboratory with and unknown concentration. A 50.0 mL sample was titrated with a standard 0.125 M H3PO4 solution. The equivalence point was reached after adding 28.38 mL of the H3PO4 solution. Write the balanced equation for the reaction of KOH with H3PO4. Calculate the concentration (in Molarity) for the KOH solution. (10 points) 7. Which of the following is the smallest atom? a) Rb b) I c) Sb d) Sn 8. Which of the following is the smallest ion? a) O-2 b) Fc) Cld) N-3 9. Briefly explain why there is a size difference (and what it is) between Mg and Mg +2. (6 points) 10. The electron affinity for Na is 52.8 kJ/mol and that for Mg is 0 kJ/mol. Why does Na “want” electrons more than Mg? (6 points)