Chemistry 121                                      Winter 2004                             Oregon State University

Final Exam                                           March 16, 2004                       Drapela

 

DO NOT OPEN THIS EXAM UNTIL INSTRUCTED.

 

Instructions: You should have with you at least one #2 pencil, a calculator, and your University ID Card. If you have electronic devices with you, turn them off, place them in a sealed backpack and place the backpack OUT OF SIGHT.

 

Scantron Instructions:

Fill in the front page of the Scantron answer sheet with your last name, first name, middle initial, and student identification number.  Leave the class section number and the test form number blank.  This exam consists of 30 multiple-choice questions.  Each question is worth 5 points.  Select the best multiple-choice answer by filling in the corresponding circle on the rear page of the answer sheet.  If you have any questions before the exam, please ask.

 

During the Exam:

If you have any questions during the exam, please raise your hand to attract the attention of a proctor.  The proctor will come to you.  You have 1 hour and 50 minutes for the exam.

 

After the Exam:

Present your ID card when submitting the exam.  You may keep this exam, so please mark the answers you selected on it.

 

R = 0.0821 L·atm/mol·K                      PV = nRT                    Avogadro’s Number = 6.02 x 1023

 

STP = 273.15 K and 1.00 atm             M1V1 = M2V2              Molar volume of a gas at STP:  22.4 L

 

P1V1/T1 = P2V2/T2                    0 ˚C = 273 K               1 atm = 760 Torr = 760 mmHg

 

PA = PTOTAL∙ XA                       4.184 J = 1 calorie                   XA = (moles A)/(total moles gas)

 

E = q + w                     DH°reaction = [S (DH°f)products] − [S (DH°f)reactants]

 

w = −P∙DV                  E = hn                          c = ln                          c = 3.00 x 108 m/s

 

1/l = RH[(1/n12) − (1/n22)]        RH = 109,678 cm−1      1 cm = 10−2 m              1 nm = 10−9 m

 

Solubility Rules:

n      Soluble compounds:

¨     All compounds of the alkali metals (Group 1)

¨     All compounds containing NH4+, NO3−, and C2H3O2− (“acetate”)

¨     All compounds containing Cl−, Br−, and I− (Except those of Ag+, Pb2+, and Hg22+)

¨     All sulfates (SO42−) (Except those of Ba2+, Pb2+, Hg22+, Ca2+, and Sr2+)

n      Insoluble compounds:

¨     All hydroxides (OH−) or (O2−) (Except those of Group 1, Ba2+, Ca2+, and Sr2+)

¨     All compounds containing PO43−, CO32−, SO32−, or S2− (Except those of Group 1, Ba2+, Ca2+, and Sr2+)

MIDTERM 1 MATERIAL

 

  1. How many significant figures are in the value 0.01050?
    1. 2                      c. 4                              e. 6     
    2. 3                      d. 5

 

  1. 1,2-epoxypentane has a density of 0.830 g/mL.  What is the volume of 100.0 g of this substance?
    1. 85.83 mL         c. 120.5 mL                 e. 177.8 mL
    2. 100.4 mL         d. 136.7 mL

 

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  1. Sodium is an example of a(n)…
    1. heterogeneous mixture  c. element                                 e. isotope
    2. homogeneous mixture               d. compound

 

  1. Two different isotopes of iron would have different…
    1. atomic numbers                        c. masses                                             e. all of the above
    2. colors                                       d. charges

 

  1. One would predict the charge of an aluminum ion to be…
    1. +1                                c. +5                                     e. −3
    2. +3                                d. −1

 

  1. The correct formula for strontium nitrate is:
    1. Sr2NO3                        c. Sr(NO3)2                              e. Sr3N2
    2. SrNO3                         d. Sr2(NO3)2

 

  1. How many molecules of water are present in a 100.0-g sample of water?
    1. 6.19 x 1023 molecules               c. 6.42 x 1024 mol                                           e. 6.02 x 1023 mol
    2. 3.34 x 1024 molecules               d. 8.93 x 1024 mol

 

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  1. How many polyatomic ions does NH4SCN contain?
    1. None                            c. Two                                             e. More than three
    2. One                              d. Three

 

 

MIDTERM 2 MATERIAL

 

  1. What is the percent composition of NH4SCN?
    1. 36.8% nitrogen, 5.3 % hydrogen, 42.2 % sulfur, 15.8% carbon
    2. 30.5% nitrogen, 4.2 % hydrogen, 48.9 % sulfur, 16.4% carbon                        
    3. 33.3% nitrogen, 4.9 % hydrogen, 38.6 % sulfur, 23.2% carbon
    4. 38.0% nitrogen, 5.0 % hydrogen, 38.2 % sulfur, 18.8% carbon
    5. 32.6% nitrogen, 4.6 % hydrogen, 42.7 % sulfur, 20.1% carbon

 

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  1. When the following equation is balanced, what is the coefficient in front of the water?

 

C2H2     +     O2 à     CO2     +     H2O

 

    1. 1                      c. 3                              e. 5
    2. 2                      d. 4     

 

  1. If unlimited BH3 is allowed to react with 65.0 g C3H6 below, how much B(C3H7)3 is formed?

 

BH3 + 3C3H6 à B(C3H7)3

 

    1. 72.1 g                          c. 85.1 g                       e. 105 g           
    2. 78.4 g                         d. 91.5 g

 

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  1. How many moles of NaOH are contained in 125 mL of a 1.50 M NaOH solution?
    1. 0.161 mol                     c. 0.243 mol                 e. 0.330 mol
    2. 0.188 mol                     d. 0.283 mol

 

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  1. If it is desired to dilute 20.0 mL of 12 M HNO3 with water to create a 1.00 M solution, to what final volume should the solution be diluted?
    1. 240 mL                        c. 340 mL                    e. 410 mL
    2. 290 mL                        d. 390 mL

 

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  1. Which of the following compounds is not soluble in water?
    1. MgSO4                        c. NaI                                  e. Ba3(PO4)2
    2. AgCl                            d. Fe(NO3)3

 

  1. Which of the following is a strong electrolyte?
    1. Water                           c. stearic acid               e. CuS
    2. NaOH                          d. CuO

 

  1. How many mL of 1.50 M HCl are needed to titrate (neutralize) 120 mL 0.20 M Ca(OH)2 solution?  (Hint:  Write and balance equation first.)
    1. 32 mL                          c. 59 mL                      e. 85 mL         
    2. 44 mL                          d. 71 mL

 

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  1. What is the volume of 40.4 g neon gas at STP?  (Neon is not diatomic.)
    1. 35.0 L                          c. 58.1 L                      e. 87.7 L         
    2. 44.8 L                         d. 71.2 L

 

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  1. A hot car engine is filled with 0.052 mol gasoline vapor (gas), 0.40 mol oxygen gas, and 0.18 mol carbon dioxide gas.  If the engine is at 350 ˚C and has a volume of 3.5 liters, what is the partial pressure of the gasoline vapor?
    1. 0.12 atm                       c. 0.37 atm                   e. 0.76 atm      
    2. 0.20 atm                       d. 0.52 atm

 

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NEW MATERIAL

 

  1. Which of the following is a measure of the average kinetic energy of the molecules in a substance?
    1. temperature                  c. heat                          e. color
    2. volume                         d. pressure

 

  1. A chemical reaction is carried out in a flask.  The flask feels cold to the touch during the reaction.  This tells you the reaction is…
    1. endothermic                  c. at equilibrium            e. insoluble      
    2. exothermic                    d. gas-forming

 

  1. Protein contains around 4,000 calories per gram.  What is this in kilojoules?
    1. 17 kJ                            c. 29 kJ                        e. 55 kJ           
    2. 23 kJ                           d. 37 kJ

 

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  1. A gas expands without losing or gaining heat.  What happens to the internal energy of the gas?
    1. It increases                               c. It remains constant                            e. Not enough info       

b.   It decreases                              d. It disappears                                     given

 

  1. The specific heat of glass is 0.84 J/g∙˚C.  If a cold pane of glass (mass = 15,000 g) at freezing temperatures (0.0 ˚C) absorbs 85,000 Joules of heat from the morning sun, how warm does it get?
    1. 7 ˚C                             c. 21 ˚C                       e. 35 ˚C          

b.   15 ˚C                           d. 29 ˚C                      

 

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  1. The specific heat of ice cream can be assumed to be about 3.2 J/g∙˚C.  If a cold scoop of vanilla ice cream (mass = 210 g, T = −9.0 ˚C) is smothered with hot fudge (mass = 120 g, T = 45 ˚C), and they both reach a final temperature of 6.8 ˚C, what is the specific heat of hot fudge?
    1. 0.93 J/g∙˚C                   c. 2.3 J/g∙˚C                 e. 4.0 J/g∙˚C    

b.   1.7 J/g∙˚C                     d. 3.0 J/g∙˚C                

 

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  1. 24.0 g of CH4 are reacted with oxygen in a calorimeter.  The temperature goes up by 32.0 degrees.  How much work is done by the system (the chemicals)?
    1. none                             c. 180 J                        e. 320 J           

b.   82 J                              d. 250 J                       

 

  1. A 100-watt light bulb is brighter than a 60-watt light bulb.  This is because:
    1. the 100-watt bulb emits more energetic photons.
    2. the 100-watt bulb emits faster photons.
    3. the 100-watt bulb emits photons with a higher frequency
    4. the 100-watt bulb emits more photons per second.
    5. the 100-watt bulb is made of tungsten.

 

  1. Use the table of Standard Heats of Formation below to calculate the heat released when 1 mole of acetone [(CH3)2CO] burns, as below.

 

 

(CH3)2CO (l)

CO2 (g)

H2O (g)

DHf˚ (kJ/mol)

−248.1

−394

−241.8

 

(CH3)2CO (l)    +     4O2 (g) à     3CO2 (g)    +     3H2O (g)

 

    1. 1249 kJ                                    c. 1983 kJ                                e. 2845 kJ
    2. 1659 kJ                                    d. 2090 kJ       

 

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  1. What is the wavelength of a radio wave with a frequency of 96.1 MHz (96.1 x 106 Hz)?
    1. 22.3 cm                        c. 835 cm                     e. 3.12 m         

b.   274 cm                         d. 1.40 m                    

 

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  1. Which of the following electronic transitions produces a photon of highest frequency?
    1. n = 6 à n = 5                          c. n = 6 à n = 3                      e. n = 7 à n = 1         

b.   n = 6 à n = 4                          d. n = 6 à n = 2                     

 

 

  1. What is the wavelength of a light wave produced when an electron drops from orbital n = 5 to n = 3 in a hydrogen atom?
    1. 1.03 x 10−6 m                           c. 7.76 x 10−6 m                       e. 6.84 x 10−5 m          

b.   1.28 x 10−6 m                           d. 2.81 x 10−5 m                      

 

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