Chemistry 121                                      Fall 2000                                  Oregon State University

Final Exam                                           December 6, 2000                   Drs. Nafshun and DeKock

 

DO NOT OPEN THIS EXAM UNTIL INSTRUCTED.  DO NOT SHARE CALCULATORS.

Instructions: You should have with you several number two pencils, an eraser, your 3" x 5" notecard, and your University ID Card.  You may use a TI-25X Solar calculator if you wish.  If you have notes with you, place them in a sealed backpack and place the backpack OUT OF SIGHT.

 

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 (4 pts each) and 8 open-ended questions.  Open and start this exam when instructed.  Present your ID card when submitting the exam.  Place your open-ended portion of this exam in the appropriate stack.  Place your 3" x 5" notecard in the appropriate stack.  You may keep the multi-choice portion of this exam, so please mark the answers you selected on it.    

760 mm Hg = 1 atm

STP is 273.15 K, 1.0 atm  (1.0 mole of gas occupies 22.4 L at STP)

R = 0.0821 L · atm/mol · K

c = 3.00 x 108 m/s

NA = 6.02 x 1023

1 in = 2.54 cm

h = 6.626 x 10-34 J•s/photon

1 m = 109 nm

K = ºC + 273.15

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Please read each question carefully.

 

1.         A student obtains a sample of gold.  She measures the volume of the sample to be 72.75 cm3.

Expressed in in3, the volume of the sample is:

 

            (A)       0.2253 in3.

            (B)       4.439 in3.

            (C)       28.64 in3.

            (D)       184.8 in3.

            (E)       1192. in3.

 

 

2.         25Mg2+ (the magnesium ion) has:

 

            (A)       10 electrons.

            (B)       11 electrons.

            (C)       12 electrons.

            (D)       13 electrons.

            (E)       14 electrons.

 

 

3.         19F- (the fluoride ion) has:

           

            (A)       7 neutrons.

            (B)       8 neutrons.

            (C)       9 neutrons.

            (D)       10 neutrons.

            (E)       11 neutrons.

 

 

4.         Which of the following sets of elements is expected to have similar chemical properties?

 

            (A)       Sulfur and phosphorous.

            (B)       Sulfur and oxygen.

            (C)       Sulfur and chlorine.

            (D)       Sulfur and argon.

            (E)       Sulfur and sodium.

 

 

5.         The chemical formula of potassium carbonate is:

 

            (A)       CK4.

            (B)       K4C.

            (C)       KCO3.

            (D)       K(CO3)2.

            (E)       K2CO3.

 

 

 

6.         Which of the following sets of elements will form an ionic compound?

 

            (A)       Na and Mg.

            (B)       Na and F.

            (C)       Ca and Mg.

            (D)       He and Na.

            (E)       C and O.

 

 

7.         When combined with lithium, a Group 7 (VIIA) element will tend to:

 

            (A)       Gain one electron.

            (B)       Gain two electrons.

            (C)       Gain seven electrons.

            (D)       Lose one electron.

            (E)       Lose two electrons.

 

 

8.         CH3CH2CH2CH2CH2OH is:

 

            (A)       an alkane.

            (B)       an alkene.

            (C)       an alkyne.

            (D)       an alcohol.

            (E)       an ether.

 

 

9.         Which of the following is an acid?

 

            (A)       Na2SO4.

            (B)       CH3CH3.

            (C)       NaOH.

            (D)       CH3OCH3.

            (E)       CH3COOH.

 

 

10.       The formula mass (also known as molar mass) of calcium sulfide is:

 

            (A)       72.14 g/mol.

            (B)       104.20 g/mol.

            (C)       112.22 g/mol.

            (D)       136.14 g/mol.

            (E)       6.02 x 1023 g/mol.

 

 

 

 

 

 

11.       A student obtains a 220 gram sample of carbon dioxide.  There are:

 

            (A)       2 moles of carbon dioxide present.

            (B)       4 moles of carbon dioxide present.

            (C)       5 moles of carbon dioxide present.

            (D)       44 moles of carbon dioxide present.

            (E)       110 moles of carbon dioxide present.

 

 

 

 

 

12.       The chemical formula of sulfur hexafluoride is:

 

            (A)       SF6.

            (B)       S2F6.

            (C)       SPF6.

            (D)       NaHCF6.

            (E)       SHF6.

 

 

13.       A student places one mole of Ca(NO3)2 into a beaker.

 

            (A)       There is one mole of nitrate ions in the beaker.

            (B)       There are two moles of nitrate ions in the beaker.

            (C)       There are three moles of nitrate ions in the beaker.

            (D)       There are four moles of nitrate ions in the beaker.

            (E)       There are six moles of nitrate ions in the beaker.

 

 

14.       Consider the CORRECTLY BALANCED reaction for the complete combustion of C7H16 in oxygen to produce carbon dioxide and water.  When one mole of C7H16 is combusted,

 

            (A)       7 moles of O2 are consumed.

            (B)       11 moles of O2 are consumed.

            (C)       13 moles of O2 are consumed.

            (D)       16 moles of O2 are consumed.

            (E)       26 moles of O2 are consumed.

 

 

 

15.       The molarity of the calcium ion in a solution that is one molar (1.0 M) in Ca(NO3)2 is:

 

            (A)       0.5 M.

            (B)       1.0 M.

            (C)       2.0 M.

            (D)       3.0 M.

            (E)       6.0 M.

 

16.       A student places 292.3 grams of sodium chloride into a two liter volumetric flask and fills to the mark with water.  The molarity of sodium chloride is:

 

            (A)       0.500 M.

            (B)       1.000 M.

            (C)       1.500 M.

            (D)       2.000 M.

            (E)       2.500 M.

 

 

17.       A student pours 200.00 mL of a 0.7500 M NaOH solution into a 5.000-L volumetric flask and fills to the mark with water.  What is the concentration of the new solution?

 

            (A)       0.120 M.

            (B)       0.0300 M.

            (C)       0.750 M.

            (D)       1.333 M.

 

 

18.       A student obtains a 25.00 mL sample of unknown HCl (aq) and titrates it with 37.22 mL of 0.2000 M NaOH (aq) to reach the equivalence point.  The concentration of the HCl (aq) is:

 

            (A)       0.2978 M.

            (B)       0.1343 M.

            (C)       186.1 M.

            (D)       0.0054 M.

            (E)       7.446 M.

 

 

19.       A student places 7.928 grams of an unknown gas into a 2.000-L flask at 273.15 K at a pressure of 2.2253 atm.  The unknown gas is:

 

            (A)       He.

            (B)       Ar.

            (C)       O2.

            (D)       CO.

            (E)       Xe.

 

 

 

20.       Given: 2 Ag2S(s) + 2 H2O(l) → 4 Ag(s) + 2 H2S(g) + O2(g) ΔH = +595.5 kJ.  The ΔH for the reaction: Ag(s) + ½ H2S(g) + ¼ O2(g) → ½ Ag2S(s) + ½ H2O(l) is:

 

            (A)       +148.88 kJ.

            (B)       -148.88 kJ.

            (C)       +595.5 kJ.

            (D)       -595.5 kJ.

            (E)       0.00 kJ.

 

21.       A student places a gas into a 2.35-L balloon at a temperature of 23.0 °C and a pressure of 0.9875 atm.  When the temperature is reduced to -20.5 °C, the volume of the balloon is:

 

            (A)       2.10 L.

            (B)       2.00 L.

            (C)       -1.90 L.

            (D)       -2.00 L.

            (E)       -2.10 L.

 

 

 

22.       A student places 2.00 moles of O2 (g) and 1.00 mole of CH4 (g) into a 22.4-L flask at 273 K.  The pressure of O2 (g) is:

 

            (A)       1/3 atm.

            (B)       2/3 atm.

            (C)       1.00 atm.

            (D)       2.00 atm.

 

 

 

23.       Consider the following five gases:  He (g)     Ne (g)     Ar (g)     Kr (g)     Xe (g)

            Of these, the gas with the greatest velocity at room temperature is:

 

            (A)       He (g).

            (B)       Ne (g).

            (C)       Ar (g).

            (D)       Kr (g).

            (E)       Xe (g).

 

 

 

24.       How many grams of H2O are obtained when 14.0 grams of C2H4 are burned in excess O2(g)?

 

            (A)       9.00 g.

            (B)       18.00 g.

            (C)       27.00 g.

            (D)       36.00 g.

            (E)       72.00 g.

 

 

25.       A system does 500 kJ of work and takes in 200 kJ of heat.  The change in the internal energy of the system is:

 

            (A)       700 kJ.

            (B)       300 kJ.

            (C)       -300 kJ.

            (D)       -700 kJ.

            (E)       0 kJ.

26.       The energy required to heat 2.00 g of water [cp = 4.18 J/g°C] from 20 °C to 80 °C is:

 

            (A)       302 J.

            (B)       502 J.

            (C)       604 J.

            (D)       906 J

            (E)       1020 J.

 

 

 

27.       Which of the following orbitals is NOT possible?

 

            (A)       4p.

            (B)       3d.

            (C)       2d.

            (D)       2s.

            (E)       1s.

 

 

 

 

28.       The energy of one mole of red photons having a wavelength of 700 nm is:

 

            (A)       4.28 x 102 J.

            (B)       2.84 x 107 J.

            (C)       4.28 x 1016 J.

            (D)       106 kJ.

            (E)       171 kJ.

 

 

 

 

29.       Which of the following regions of electromagnetic radiation is not produced from the emission of a hydrogen atom?  (Provided figures may be helpful).

 

            (A)       X-ray.

            (B)       UV.

            (C)       Visible.

            (D)       Infrared.

            (E)       AM radio.

 

30.       Solutions to the wave equation for the hydrogen atom solved by Schrodinger led to the new concept(s) of the quantization of:

 

            (A)       Gas pressure.

            (B)       Energy and space for the electron.

            (C)       Energy only for the electron.

            (D)       Space only for the electron.

            (E)       Temperature.

Student's Name    _______________________________________________ ID number  __________________________

CH 121 Final Exam OSU                                                                                                      December 6, 2000

 

YOU MUST SHOW ALL WORK ON NUMERICAL PROBLEMS TO RECEIVE CREDIT

 

1. [4 points] A student mixes solutions of the following ions together in a beaker: Fe3+, Na+, NO3-, OH-.

 

    The correct formula of the compound which precipitates from the solution is _________________.

 

 

2. [4 points] A student burns magnesium metal in P4(gas).  The correct formula of the ionic compound

 

    which forms is _____________.

 

 

3. [4 points] A student places 1.0 mole of O2(g) and 3.0 moles of He(g) in an 11.2 L container at 273 K.

 

    The pressure in the container is _____________ atmospheres.

 

 

 

 

 

 

 

4. [4 points] When 16.0 grams of methane(CH4) are burned in O2(g), 890.3 kJ of heat is released.  How

    much heat is released when 12.04 x 1023 molecules of methane are burned in O2? 

 

 

 

 

 

 

 

 

Answer:_______________.

 

5. [4 points] Given the reaction which occurs at constant pressure of 10 atmospheres and constant

    temperature of 400 K.  C5H12(l)   +    8 O2(g)   →   5 CO2(g)   + 6 H2O(g)

 

    How many liters of H2O (g) are formed at 10 atm and 400 K when 4.0 liters of O2(g) are consumed?                                                                                               

 

 

 

 

 

 

Answer:______________

6. [4 points] The standard enthalpy of formation for one mole of ethanol, C2H5OH is -277.7 kJ/mol. 

    Write the chemical equation associated with this enthalpy of formation.

 

 

 

 

 

 

 

7. [12 points] A partial representation of the energy level diagram for the electron in the hydrogen atom

    is shown in Figure 1 on the back page of first page of the exam.  Answer the following questions

    referring to Figure 1.

 

a) The red line in the hydrogen spectrum arises when the electron falls from n=_____ to n=_____.

 

b) What energy is required to ionize a mole of H atoms from the n=3 level?   _________________.

 

c) When an electron makes a transition from n=6 to n=2 or n=5 to n=2 it yields two lines with different 

    shades of purple.  Are there other lines in the hydrogen spectrum with different shades of purple?  

 

YES   NO (Circle One)  If Yes EXPLAIN showing which values of n would be involved.

 

 

 

 

 

d) Which of the following transitions has the longer wavelength:    n=4 to n=1    or    n=6 to n=3.

(Circle One Set)

    Explain your answer in terms of the relative energies of these two transitions.

 

 

 

 

 

8. [4 points] On the set of Cartesian coordinates on the left draw the electron distribution for an electron

    in a 1s orbital.  Do the same for the electron distribution for an electron in a 2px orbital in the

    Cartesian system on the right.