Unformatted text preview: Chem101 (Bontems, Fall 2009, TTH) Exam 3 Name: __________________________ Multiple Choice – In the blank, write the letter of the best answer. You may show your work for partial credit when calculations are required. (3 pts. ea.) 1 .________ The reaction of 2A + 3B C has a ∆H of ‐10.0 kJ. The ∆H for 2C 4A + 6B is: a. + 10 kJ c. ‐10 kJ b. +20 kJ d. ‐20 kJ e. none of these 2. ________ How many unpaired electrons are there in a carbon atom? a.
0 d. 6 b.
1 e. none of these c.
2 3.________ If you burned 2.20 g Mg with excess oxygen and obtained a q = ‐54,500 J, calculate ∆H for the combustion of a mol of magnesium in kJ is: a. ‐4.93 kJ c. ‐218 kJ b. ‐54.5 kJ d. ‐602 kJ 4.________If an atom has the electron configuration 1s22s22p3, how many more electrons does it need to fill its shell? a. 0 c. 6 b. 3 d. 8 5.________A reaction gives off 100 kJ of heat and does 25 kJ of work on the surroundings. The change in energy for this reaction is: a. b. 125 kJ ‐125 kJ c. d. 75 kJ ‐75 kJ 6.________Which of the following will reach the highest T when 10 kJ of heat are added to each? a. aluminum (specific heat = 0.903) b. iron (specific heat = 0.449) c. copper (specific heat = 0.385) d. All will have the same T because the same amount of heat was added. 7. _______ How much heat must be added to 50.0 g of water (4.18 J/g°C) to raise the temperature from 20.00°C to 30.00°C? a. 2090 J c. 120. J b. 41.8 J d. none of these 8. _______ Given the following reaction information, calculate ∆H for reacting 10.0 g of ammonia with excess oxygen. 4NH3 + 5O2 4NO + 6H2O ∆H = ‐902.0 kJ a. ‐90.2. kJ d. ‐22.6 b. ‐361 kJ e. none of these c. ‐133 kJ 2 9. _______ Which is true of Photon X (λ = 750 nm) and Photon Y (λ = 650 nm)? a. Y has higher frequency and lower E. b. Y has higher frequency and higher E. c. Y has lower frequency and lower E. d. Y has lower frequency and higher E.. 10. _______ Of the following transitions in the Bohr hydrogen atom, the ______ transition results in the absorption of the highest energy photon. a. n= 5 → n = 1 d. n=1 → n=5 b. n = 6 → n = 4 e. n = 1 → n =4 c. n = 3 → n = 2 11. _______ The _______ quantum number defines the shape of an orbital a. n c. l d. ms b. ml 12. _______ Which of the following values is not a valid value for m of an electron in a 5d subshell? a. 1 c. ‐2 b. ‐1 d. 0 e. all of these are valid 13. _______ The _______ subshell contains 5 orbitals. a. 4d c. 5s b. 5p d. 6f e. none of these 14. _______ Each f‐subshell can accommodate a maximum of ___ electrons. a. 2 c. 6 b. 3 d. 10 e. none of these 15. ________ Which of the following quantum numbers represents an s orbital? a. n = 4, = 3, m = 1 c. n = 3, = 1, m = 0 b. n = 3, = 2, m = 1 d. none of these 16. _______ What is the maximum number of electrons with ms = +½ that can be in the n = 2 shell of an atom? a. 1 d. 18 b. 4 e. none of these c. 9 17. ________ Which set of quantum numbers is not allowed? a. n = 3, = 0, m = 0, ms = + ½ b. n = 3, = 2, m = 1, ms = ‐ ½ c. n = 1, = 1, m = ‐1, ms = ‐ ½ d. n = 2, = 1 , m = ‐1, ms = + ½ 18. Write a full electron configuration for carbon. (3 pts) 3 19. Write condensed configurations for each of the following: (6 pts) Mo (#42) Hg (#80) 20. Both vanadium (V #23) and V+3 are paramagnetic. Draw orbital diagrams from [Ar] on for each of these and explain why they are paramagnetic. Be sure to define paramagnetic. (5 pts) 0 21. Which element has the configuration [Kr]5s2? _______ (3 pts) 22. Which is larger and why? (6 pts) ‐1 F or Ne Na or K 23. Which has higher first ionization energy, Na or Rb? (6 pts) For Na, write the first three chemical equations representing ionization energy. Where will you find the largest increase in the above series and why? 24. Calculate the final temperature of 25.0 g of silver (Cs = 0.235 J/g°C) initially at 27.0 °C after you add 2.35 kJ of heat. (5 pts) 4 25. Write a balanced equation representing the heat of formation of silver carbonate. (3 pts) 26. What mass of CO2 (44.0 g/mol) would be produced when you use 4,000.0 kJ of heat to warm a room by burning propane (C3H8)? C3H8 + 5O2 3CO2 + 4 H2O ∆H = ‐2217 kJ (5 pts) 27. Calculate the mass of hot copper at 99.0°C needed to heat a cup of 120.0 g of cold coffee at 30.0°C to a better drinking temperature of 60.0°C, given that the specific heat of coffee is close to 4.18 J/g°C and copper is 0.385 J/g°C. This experiment was done in a coffee‐cup! (5 pts) 28. Find the enthalpy change, ∆H, for this reaction given the following information. Show your work. (4 pts) Fe2O3(s) + 3CO(g) 2Fe(s) + 3CO2 ∆H (kJ) (a) 2Fe(s) + 3 2O2(g) Fe2O3(s) ‐824.2 ‐282.7 (b) CO(g) + ½ O2 (g) CO2(g) Bonus: Describe the white solid demo that smelled like ammonia, the hydrogen balloon demo, the alkalai metal video clip and fluorescent bulb demonstrations. Include what you saw and the science behind the demo. ...
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- Fall '11
- Reaction, 10.0 g, 25.0 g, 100 kJ, 2.20 g, 54.5 kJ, 133 kJ