Lab Day and Time: Instructions. 1. Do not open the exam until you are told to start.

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1 Name: Lab Day and Time: Instructions 1. Do not open the exam until you are told to start. 2. This exam is closed note and closed book. You are not allowed to use any outside material while taking this exam. 3. Use the spaces provided to write down your answers. To receive full credit, you must show all work. Do not write answers on any other pieces of paper. If you need more room, write on the back of the exam and be sure to include a note describing where the work is located. 4. When solving numerical problems, make sure you include the proper units in your final answer. 5. If a question asks for a response in sentence or paragraph form, make sure you respond in that format. 6. Useful data for the exam and a periodic table are provided on the last page of the exam. Carefully tear out these sheets if you wish. Page # Points possible Points awarded EC 2 Attendance 3 Total 100 1

2 Multiple Choice Unless otherwise directed, choose the single best answer for each question. All problems are worth 3 points except one is worth four points. 1. A M NaOH solution contains moles of NaOH. What is the volume (ml) of the solution? a.) 6849 ml b.) ml c.) ml d.) ml 2. A sealed flask contains a mixture of He(g) and Ne(g) at a total pressure of 2.6 atm. There are 2.0 moles of He and 5.0 moles of Ne in the flask. What is the partial pressure of He (atm.) in the flask? a.) 1.9 atm. b.) 6.5 atm. c.) 1.0 atm. d.) 0.74 atm. 3. Use the chemical equation below to calculate the moles of AlBr 3 that will be formed when 3.0 mole of Br 2 is reacted with an excess of Al. Al(s) + Br 2 (g) AlBr 3 (s) a.) 2.0 mol b.) 3.0 mol c.) 4.0 mol d.) 6.0 mol 4. A ml solution of M H 2 SO 4 is titrated with a M solution of KOH. What volume of KOH must be added to react with all of the H 2 SO 4? a.) ml b.) ml c.) ml d.) ml e.) None of the above 2

3 When bromine reacts with water vapor, it produces HBr and O 2. The balanced chemical equation for this reaction is shown below. Use this equation and the diagrams below to answer the following three questions. It may be easier to solve the problems if you figure out what is in the container after the reaction. 2H 2 O(g) + 2Br 2 (g) 4HBr(g) + O 2 (g) hydrogen bromine oxygen Before Reaction 5. Which compound is the limiting reagent? After Reaction a.) Br 2 b.) O 2 c.) HBr d.) H 2 O 6. Assuming the temperature and volume of the container remain constant over the course of the reaction, what happens to the pressure? a.) The pressure remains constant. b.) The pressure increases. c.) The pressure decreases. d.) None of the above. 7. In order for two chemicals to react with each other, they must collide. The speed or rate of a reaction depends on how often the reactants collide with each other (the greater the frequency of collisions, the faster the reaction). What will happen to the rate of the reaction described in the diagrams above if the temperature is decreased by 100ºC? a.) The speed or rate of the reaction will increase. b.) The speed or rate of the reaction will decrease. c.) The speed or rate of the reaction will not change. d.) None of the above. 8. How many unpaired electrons are there in the molybdenum (Mo) atom? (3 points) a.) 1 d.) 5 b.) 2 c.) 4 3

4 9. When a 1.25 L solution of M MgCl 2 is mixed with excess AgNO 3, what is the mass of AgCl that is produced? MgCl 2 (aq) + 2AgNO 3 2AgCl(s) + Mg(NO 3 ) 2 (aq) Molar Mass (g/mole) a.) 71.7 g b.) 89.6 g c.) 35.8 g d.) 44.0 g 10. What is the volume of a helium balloon that contains 2.50 moles of He at 27 C and 1.10 atm.? a.) 5.04 L b.) 22.4 L c.) 34.8 L d.) 56.0 L 11. How many valence electrons does Se contain? a.) 14 d.) 2 b.) 6 c.) A chemist adds ml of deionized water to a beaker that contains ml of a 2.50 M K 2 C 2 O 4 solution. How many moles of K 2 C 2 O 4 are in the beaker? a.) moles of K 2 C 2 O 4 b.) moles of K 2 C 2 O 4 c.) 2.50 moles of K 2 C 2 O 4 d.) moles of K 2 C 2 O 4 e.) None of the above 4

5 Shown below are energy level diagrams for arsenic (As), iron (Fe), and lithium (Li). In the diagrams, a valence electron is shown in the ground state right before the atoms are exposed to visible light. Once exposed to the light, each electron is promoted to an excited state. Use the diagrams to answer the following question. Energy e e - e If arsenic absorbed a photon of only blue light, iron absorbed a photon of only orange light, and lithium absorbed a photon of only red light, which diagram represents the energy level diagram for arsenic? a.) Diagram 1. b.) Diagram 2. c.) Diagram 3. d.) They could all represent arsenic. 14. Sodium hydride reacts with water to produce aqueous sodium hydroxide and hydrogen gas. When a sample of NaH(s) is added to a beaker of water, 982 ml of H 2 (g) is collected in a container above the water. If the pressure inside the container is 765 mmhg and the temperature of the water and gas is C, what mass of sodium hydride must have reacted? (4 points) NaH(s) + H 2 O(l) NaOH(aq) + H 2 (g) Molar Mass (g/mole) a.) g b.) 2.93 g c.) g d.) g 5

6 15. In the space provided below, draw a picture of one 3d orbital and one 4d orbital. Make sure to label which picture corresponds to the 3d orbital and which one corresponds to the 4d orbital and to point out the location of the nucleus. (3 points) 16. Fill in the blank with the chemical formula(s), word(s), phrase, or number(s) that best completes the sentence. (6 points) Put your answer on this side. a.) Under i) temperature and ii) pressure, gases do not behave as ideal gases. (high, low, or moderate) b.) The condensed electron configuration of Sn is. i.) ii.) 17. In the space provided below, give the condensed orbital box diagram for nitrogen and oxygen, and then answer the following questions. (a condensed orbital box diagram would be the same as the condensed electron configuration but includes boxes for orbitals) (7 points) a.) N: b) O: c.) Based on the material that was presented in class, which of the two atoms would you expect to have the largest ionization energy and why? d.) It turns out that the general pattern is not followed in the case of nitrogen and oxygen. Use the difference in the orbital box diagrams to briefly explain why the general trend is not followed. 6

7 18. One of the steps in the commercial process for converting ammonia to nitric acid is the conversion of NH 3 to NO and H 2 O as indicated by the balanced chemical equation shown below. 4 NH 3 (g) + 5 O 2 (g) 4 NO(g) + 6 H 2 O(g) Molar Mass (g/mole) a.) If you start with 2.25 g of NH 3 and 3.75 g of O 2, what mass of H 2 O will you generate? (14 points) b.) How much of each reactant will be left after the reaction is complete? (5 points) c.) If the actual yield of H 2 O(g) was 2.00 g, what was the percent yield of the reaction? (2 points) 7

8 19. A ml sample of arsenic acid is titrated with M NaOH. The balanced titration reaction is shown below. H 3 AsO 4 (aq) + 3NaOH(aq) 3H 2 O(l) + Na 3 AsO 4 (aq) a.) If the titration requires ml of the NaOH solution to reach the equivalence point, how many moles of H 3 AsO 4 were in the original arsenic acid solution? (7 points) b.) What was the molarity of the original H 3 AsO 4 solution? (3 points) c.) If the end point of the titration was dark pink in color, would the value for the calculated molarity be too large, too small, or unaffected? (3 points) 20. In the table below, the name or formula for a chemical compound is given. Fill in the table with the corresponding name or formula of the chemical compound. (4 points) NAME FORMULA Sr(C 2 H 3 O 2 ) 2 aluminum hydroxide 8

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11 Conversion Factors, Constants, and Periodic Table Avogadro s Number: Pressure Conversion: Ideal Gas Constant: Temperature conversion: x particles/mole 760 mmhg (torr) = 1 atm L atm mol K L mmhg mol K J mol K T [K] = T [ C] Percent Yield: actual yield % yield 100% theoretical yield Gas Equations: P A P tot χ A Vapor Pressure of Water at Various Temperatures Temperature ( C) Vapor Pressure (mmhg) Compound Molar Mass (g/mole) AgCl AgNO Na 2 SO P PV nrt 1 H Li Na K Rb Cs Fr (223) 4 Be Mg Ca Sr Ba Ra Sc Y La Ac Ti Zr Hf Rf (261) 23 V Nb Ta Db (262) 24 Cr Mo W Sg (263) 25 Mn Tc (98) 75 Re Bh (262) 26 Fe Ru Os Hs (265) 27 Co Rh Ir Mt (266) 28 Ni Pd Pt Uun (269) 29 Cu Ag Au Uuu (272) 30 Zn Cd Hg Uub (277) 5 B Al Ga In Tl C Si Ge Sn N P As Sb O S Se Te F Cl Br I He Ne Ar Kr Xe Pb Bi Po At Rn (209) (210) (222) Ce Th Pr Pa Nd U Pm (145) 93 Np (237) 62 Sm Pu (244) 63 Eu Am (243) 64 Gd Cm (247) 65 Tb Bk (247) 66 Dy Cf (251) 67 Ho Es (252) 68 Er Fm (257) 69 Tm Md (258) 70 Yb No (259) 71 Lu Lr (260) 11