Department of Chemistry, Geosciences and Environmental Sciences

 

                                                                     Exam 4-A-Key

                       

Chemisty 1084:  Section 010 & 030                                                                       Spring 2007

 

Name:________________________________________________________

 

Read all directions and questions carefully!!  This exam consists of two parts.  The first part consists of 10 multiple choice questions worth four points each for a total of 40 points.  The second part consists of five numerical problems worth either 10 or 15 points per question for a total of 60 points.  Show all your work necessary for the numerical problems as partial credit will be given for those problems.

 

Possibly Useful Constants and Equations

 

                        Speed of light in a vacuum:  c = 2.998 × 108 m/s

 

                        E = mc2                                                                              1 amu = 1.661 × 10-27 kg

                                               

 

 

Score

 

                                    Part 1 (40 points):_____________________

 

 

                                    Part 2 (60 points):_____________________

 

 

                                    Total (100 points):_____________________

 

 

Don’t forget to put your name on this test!

 

Good Luck!!


Part 1

 

Multiple Choice

 

Please indicate the answer to each question by putting your choice in the space provided.  There is only one correct answer for each question.  There will be 10 multiple choice questions worth 4 points each.

 

1.  Atoms with the same atomic number and different mass numbers

       (a)  do not exist.                                                          (c)  are isotopes.

       (b)  are isomers.                                                         (d)  are allotropes.

                        (e)  are resonance structures.

 

Answer:  C

 

2.  The nuclear reaction below shows how 14C is created in the upper atmosphere.  What is the missing particle in this reaction?

       (a)  an alpha particle                                                  (c)  an electron

       (b)  a neutron                                                              (d)  a positron

                        (e)  a proton

 

Answer:  B

 

3.  If, on average, one product neutron in a fission reaction causes an additional fission reaction, the situation is called:

       (a)  critical                                                                 (c)  subcritical

       (b)  supercritical                                                         (d)  moderated

 

Answer:  A

 

4.  What is the hybridization associated with a doubly bonded carbon atom in a hydrocarbon?

       (a)  sp3                                                                        (c)  dsp3

       (b)  sp                                                                         (d)  sp2

                                                            (e)  d2sp3

 

Answer:  D

 

5.  The way that protein chains wrap around each other is called a protein’s _________________ structure.

       (a)  primary                                                                (c)  tertiary

       (b)  secondary                                                             (d)  electronic

 

Answer:  B

 

 

 


6.  The strands in DNA are held together by:

       (a)  ionic-dipole forces                                              (c)  covalent bonds

       (b)  coordinate covalent bonding                                (d)  London dispersion forces

                                        (e)  hydrogen bonding

 

Answer:  E

 

7.  Processes that use heat to refine or reduce metal ores are collectively referred to as:

       (a)  hydrometallurgy                                                   (c)  pyrometallurgy

       (b)  electrometallurgy                                                 (d)  roasting

                                                            (e)  calcination

 

Answer:  C

 

 

8.  What is the major reducing agent in a blast furnace used to produce iron metal from iron ore?

       (a)  CO2(g)                                                                  (c)  coke

       (b)  limestone                                                             (d)  CO(g)

                                                            (e)  H2O(g)

 

Answer:  D

 

9.  Which of the following compounds contains oxygen in the –1 oxidation state?

       (a)  CO2                                                                      (c)  Na2O2

       (b)  KO2                                                                      (d)  O2

 

Answer:  C

 

10.  The primary commercial use of hydrogen is:

(a)  as a rocket fuel, especially on the space shuttle.

(b)  hydrogenation of vegetable oils.

(c)  the manufacture of ammonia.

(d)  as an automobile fuel.

(e)  in lighter than air balloons.

 

Answer:  C

 

 

 


Part 2

 

Numerical Problems

 

Solve the following problems, keeping track of significant figures where applicable.  Please show all the work necessary to obtain your answer in order to receive partial credit for possibly wrong answers.  Generally, full credit will not be given for the correct answer without any of the work performed to obtain the answer being shown on the paper.  Each question is worth either 10 or 15 points.

 

 

11.  (10 points)  Complete the following nuclear reactions by writing the symbol for the missing nuclide:

 

(a) 

 

(b) 

(c) 

 

(d) 


12.  (15 points)  Either give the official IUPAC name for the structure or write the structure given the official IUPAC name for the following hydrocarbons:

 

(a)                                          2,3-dimethylpentane

 

(b)  3-ethyl-3-methylheptane                                  

 

 

 

(c)                 5-ethyl-2-methyloctane

 

 

(d)  trans-2-pentene

 


13.  (10 points)  For each of the following two compounds containing coordination complexes give: the number of ions produced per formula unit when the compound is dissolved in water;  the coordination number about the transition metal in the coordination complex; and the oxidation number for the transition metal.

 

       (a)  [Zn(NH3)3Cl]Cl                                                (b)  [Cr(H2O)5Cl]Cl2

Number of ions produced:                                       Number of ions produced:

[Zn(NH3)3Cl]Cl  ® [Zn(NH3)3Cl]+  +  Cl¯             [Cr(H2O)5Cl]Cl2 ®  [Cr(H2O)5Cl]2+  +  2 Cl¯

2 ions                                                                      3 ions

Coordination number:                                             Coordination number:

4 ligands are attached to Zn:  4                               6 ligands are attached to Cr:  6

Oxidation number:                                                   Oxidation number:

Overall charge on complex +1                                Overall charge on complex:  +2

(Oxidation number of Zn) + 3×0 + –1 = +1             (Ox. Num. of Cr) + 5×0 + –1 = +1

Oxidation number of Zn = +2                                  Oxidation Number of Cr = +3

14.  (10 points)   Circle and identify the functional groups contained in the organic compounds shown below.  A molecule may contain more than one functional group.  The possible choices include:  alcohol, aldehyde, alkyl halide,  amide, amine, carboxylic acid, ether, ester, and ketone


15.  (15 points)  Analysis of an extinct animal species found in Australia had a 14C activity of 1.33 disintegrations per minute per gram of material.  Given a 14C activity of 15.0 disintegrations per minute per gram in living animals, estimate how many years ago this animal died.  The half-life of 14C is equal to 5715 years. 

Use the equation: 

Calculate the value of k: 

A0 = 15.0, A = 1.33.  Plug in the known values and solve for t:

 


For 10 points extra credit: 

Define 2 of the following 3 terms.  Please remember to choose only 2 of the choices, if you answer all 3 with no indication of which 2 you want graded, only the first two definitions will be graded.  Each complete definition is worth 5 points.  No partial credit will be given.

 

Linkage isomers:  two coordination complexes in which a ligand is attached via a different atom.

 

 

Roasting:  heating an ore until it reacts with the furnace atmosphere

 

 

Nuclear transmutation:  changing one element into another via a nuclear reaction.