Leader: Katie Exam 3 Review Course: Chem 177 Supplemental Instruction Instructor: Burnett Iowa State University Date: April 1st, 2010 1. From the enthalpies of reaction 퐻2 푔 + 퐹2 푔 → 2퐻퐹 푔 ∆퐻 = −537 푘퐽 퐶 푠 + 2퐹2 푔 → 퐶퐹4 푔 ∆퐻 = −680 푘퐽 2퐶 푠 + 2퐻2 푔 → 퐶2퐻4 푔 ∆퐻 = 52.3 푘퐽 Calculate ∆퐻 for the reaction of ethylene with 퐹2: 퐶2퐻4 푔 + 6퐹2 푔 → 2퐶퐹4 푔 + 4퐻퐹 푔

2. Calculate the standard enthalpy change for the following reaction using the values given in the table below. 2푆푂2 푔 + 푂2 푔 → 2푆푂3 푔 푆푂2 푔 -296.9 푆푂3 푔 -395.2 퐻2푂 푙 -285.8

3. Indicate whether each of the following statements is True or False. a) ______Longer wavelengths of electromagnetic radiation correspond to greater frequencies. b) ______Photon energies decrease with increasing wavelength. c) ______The energy transmitted by electromagnetic radiation is quantized.

4. In the Bohr model of the atom ______. a) A single photon is absorbed when an electron moves from a low energy orbit to a higher energy orbit. b) Electrons freely roam throughout the volume of the atom. c) Electrons exist simultaneously in multiple orbits. d) Energy is absorbed when electrons fall to orbits close to the nucleus. e) Line spectra cannot be predicted for the hydrogen atom.

5. The light-sensitive substance in black-and-white photographic film is AgBr. Photons provide the energy necessary to transfer an electron from 퐵푟− 푡표 퐴푔+ to produce Ag and Br and darken the film. 2.00 x103 J/mol is the minimum amount of energy required for this process. a) Calculate the energy in Joules that a single photon must have to for this process to occur.

Supplemental Instruction 1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu b) Calculate the wavelength in meters of a single photon necessary to provide photons of this energy.

6. Calculate the wavelength (in nm) of light when an electron moves from the n = 2 to the n = 4 energy level.

7. Which one of the following processes are thermodynamically favored. a) An endothermic process. b) The burning of wood. c) Melting of iron. d) All of the above.

8. [Ar] 4푠23푑104푝3 is the electron configuration of a(n) ______atom. a) As b) V c) P d) Sb e) Sn

9. In general, as you go across a period in the periodic table from left to right: 1) The atomic radius ______. 2) The electron affinity becomes ______negative. 3) The first ionization energy ______.

a) decreases, decreasingly, increases b) increases, increasingly, decreases c) increases, increasingly, increases d) decreases, increasingly, increases e) decreases, increasingly, decreases

10. Of the following elements, ______has the most negative electron affinity. a) Na b) Li c) Be d) N e) F

11. Of the following species, ______has the largest radius. a) 푅푏+ b) 푆푟2+ c) 퐵푟− d) 퐾푟 12. Write the full electron configuration of the chromium atom.

13. Draw the shape of a 4p orbital. Clearly indicate the nodes.

14. Which one of the following sets of quantum numbers (n, l, 푚푙, 푚푠) corresponds to an electron in a 3p orbital? a) 3, 3, -1, - 1/2 b) 3, 0, 0, +1/2 c) 3, 1, +1, -1/2 d) 4, 3, 0, +1/2

15. Write balanced equations for the following reactions. a) Potassium oxide with water.

b) Diphosphorus trioxide with water.

c) Chromium (III) oxide with dilute bydrochloric acid.

d) Selenium dioxide with aqueous potassium hydroxide.

16. Write a balanced equation for the reaction that occurs in each of the following cases: a) Potassium metal burns in an atmosphere of chlorine gas.

b) Strontium oxide is added to water.

c) A fresh surface of lithium metal is exposed to oxygen gas.