Chem 121 Rybolt Exam 1 Fall 2006 Name_________________________________
Numerical constants may be listed below. Other needed information is given in the problem or written on
the board or found in the periodic tables you will use during exam. For numerical problems, be sure to
show your work, include units and circle your final answer. If several choices are given, circle the
correct answer. Your written answers should be brief - just a few key words or sentences and not a long
discussion. You can use a calculator on the exam, but no notes, books, external information, or other
electronic devices are to be used.
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1) Rhenium (Re) is element number 75 on the periodic table and was discovered in 1925 by
scientists who detected Re in platinum ore. Later in 1928 they were able to extract 1 gram of Re
from 660 kg of the mineral molybdenite which is molybdenum (IV) sulfide MoS2. Today
rhenium is used to make temperature measuring devices called thermocouples and is also found
in oven filaments.
In nature rhenium is found as two isotopes 37.40% 185Re and 62.60% 187Re. Assume the 185 and
187 are exact and find to (4 significant figures) the average mass of rhenium.
2) What are the number of protons and number of neutrons in 185Re ?
3) What are the number of protons and electrons in 187Re2+ ?
4) Where are the protons and neutrons found in an atom of Re
around outside
spread throughout
in center
5) What experiment led to the knowledge of the location of the protons in an atom?
6) If rhenium is heated above its melting point of 3186oC, and it changes from a solid to a liquid
this is a chemical change
physical change
combustion
elemental change
7) If rhenium is combined with fluorine to make rhenium(II) fluoride, this is a
a chemical change
physical change
combustion
elemental change
8) Write a balanced chemical equation (using element and compound symbols) to represent the
reaction
rhenium plus fluorine to make rhenium(II) fluoride
+

9) Write the correct atomic symbol for the following
tungsten
carbon
10) Write the correct name for the following
S
Si
11) The element I may be classified as
alkali metal
alkaline earth halogen
noble gas
12) Write and balance the following chemical reaction
methane
+ oxygen 
carbon dioxide
13) The element S may be classified as
metal
nonmetal
14) Name the following
C4H10
+
water
metalloid
NH3
15) Name the following
ZnO
16) Name the following
CuSO4
NaHCO3
17) Write the correct formula for
dinitrogen trioxide
uranium hexafluoride
18) Name the following compounds
HNO3
NaClO
CaI2
19) If an ion contains one carbon atom and one unknown atom per ion and the percent mass of
carbon is 46.15% and the unknown is and 53.85%, then determine the mass (amu) of the
unknown atom if the mass of a single carbon atom is 12.00amu.
20) If a Honda Civic Hybrid is is driven 456.7 miles and uses 11.1gallons of gasoline then what
is the miles per gallon (mpg) to the correct number of significant figures ?
21) If the density of gasoline is 730kg/m3 then determine the density expressed in pounds per
gallon (lb/gal). You need to know that there are 454g in 1.00lb, 1000L in 1.00m3, 1.00L in
1.06qt (quart), and exactly 4 quarts in 1.00 gallon.
22) Use the temperature conversion formula oC = (oF - 32)/1.8 and convert the melting point of
rhenium of 3186oC from Celsius to Fahrenheit.
23) Gasoline has many different molecules that do not separate into different layers in a liquid
therefore we call this
pure element
pure compound heterogeneous mixture
homogeneous mixture
24) If you are 5 feet (ft) and 10 inches (in) tall then your height in meters is (Recall that there are
2.54 cm in 1.00 in).
25) If you travel 7.1 miles to work then you have traveled how many meters. (Recall that there
are exactly 2.54cm per one inch, 5280ft per mile.)
26)) According to Democritus in ancient times and John Dalton in 1808, the building blocks of
nature are