CHEM 121
General Chemistry
Summer 2012
Name:
Midterm Examination 1
Multiple Choice, etc.
1.
The following:
The elemental composition of a given compound is always fixed, no matter the
method of preparation or isolation.
is an example of a:
a)
b)
c)
d)
2.
Rutherford's Gold Foil Scattering experiment:
a)
b)
c)
d)
3.
Theory.
Natural Law.
simple Quantitative Experimental result.
simple Qualitative Experimental result.
determined the charge on the electron.
determined the charge on the neutron.
demonstrated the nuclear structure of the atom.
demonstrated the existence of the neutron.
Perform the following unit conversion:
3.87 ng = ? mg
a)
b)
c)
d)
4.
3.87 x 10-2 mg
3.87 x 10-4 mg
3.87 x 10-6 mg
3.87 x 10-8 mg
Perform the following unit conversion:
4.13 cm3 = ? km3
a)
b)
c)
d)
4.13 x 10-6 km3
4.13 x 10-9 km3
4.13 x 10-12 km3
4.13 x 10-15 km3
5.
The mass standard for atoms is a 12C atom, which is assigned a mass of 12 amu.
What is this mass in terms of the mass standard for ordinary objects, the kilogram?
a)
b)
c)
d)
6.
The volume of a liquid is measured with a graduated cylinder and is reported as
2.34 mL. This graduated cylinder is graduated (marked) to:
a)
b)
c)
d)
7.
1.57 x 1021 kg
2.11 x 1019 kg
1.99 x10-23 kg
3.77 x 10-22 kg
1 mL
0.1 mL
0.01 mL
0.001 mL
The difference between the two mass measurements below:
32.9283g - 2.73g
will contain how many significant figures?
a)
b)
c)
d)
8.
2
3
4
5
The compound Plumbous Plumbate is 89.62% Lead and 10.38% Oxygen. How
much Oxygen is required to react with 8.00g of Lead?
a)
b)
c)
d)
0.57 g.
0.79 g.
0.93 g.
1.23 g.
9.
Alcohol boils at 78.5oC. This is:
a)
b)
c)
d)
a chemical property of Alcohol.
an extensive physical property of Alcohol.
an intensive physical property of Alcohol.
not a characteristic property of Alcohol.
10. Sugar-Water is an example of a:
a)
b)
c)
d)
heterogeneous system.
solution.
compound.
(a) and (b).
11. Oil and Vinegar dressing is an example of a:
a)
b)
c)
d)
heterogeneous system.
homogeneous system.
solution.
compound.
12. Column Chromatography can be used to separate the pigments in the leaves of
Spinach. It is found the Carotenoid pigments will move faster along the column
than the Chlorophyll pigmennts. This implies:
a)
b)
c)
d)
the Carotenoids have a higher affinity for the solid support that the Chlorophylls.
the Chlorophylls have a higher affinity for the eluting solvent than the Carotenoids.
the Carotenoids have a lower affinity for the eluting solvent than the Chlorophylls.
the Carotenoids have a lower affinity for the solid support than the Chlorophylls.
13. Elemental Argon (Ar) is a:
a)
b)
c)
d)
gaseous non-metal.
liquid non-metal.
liquid metal.
solid metal.
14. Elemental Zirconium (Zr) is a:
a)
b)
c)
d)
liquid metal of Group 4B.
solid metal of Group 4B.
solid non-metal of Group 4B.
liquid non-metal of Group 4B.
15. For the following compound:
Ca3(PO4)2
how many atoms of each constituent element is contained in a "molecule" of the
compound?
Calcium
Phosphorus
Oxygen
16.
Nitrogen reacts with Oxygen to form several different compounds. Two of these are
Nitrous Oxide and Nitric Oxide. The chemical formulas of these compounds are:
Nitrous Oxide:
Nitric Oxide:
N2O
NO
If 1.00g of Oxygen is consumed, 1.75g Nitrogen is needed to form Nitrous Oxide.
If, again, 1.00g of Oxygen is consumed, how much Nitrogen is required to form
Nitric Oxide?
a)
b)
c)
d)
17.
1.138g
2.112g
0.875g
0.544g
An atom of 75As contains how many protons?
a)
b)
c)
d)
75
99
23
33
18.
An atom of 51V contains how many neutrons?
a)
b)
c)
d)
51
23
28
99
19. An atom of S2- contains how many electrons?
a)
b)
c)
d)
20.
16
79
18
99
The mass of an atom is determined primarily by:
a)
b)
c)
d)
the electrons and protons contained in the atom.
the neutrons and electrons contained in the atom.
the neutrons and protons contained in the atom.
the protons contained in the atom.
21. In rough terms, if an atom were the size of a typical sports stadium, the nucleus is
the size of a:
22. The ions 63Cu+ and 63Cu2+ differ in their:
a)
b)
c)
d)
masses.
numbers of neutrons.
numbers of protons.
numbers of electons.
23. Indicate if the following postulates of Dalton's Atomic Theory continue to hold in
their entirety; i.e., are True or False.
Atoms of a given element are alike.
Atoms of different elements differ in their properties, such as mass,
volume, etc.
24. Provide a name for the following compound:
Cr3(PO4)2
25. What is the chemical formula for Mercuric Chloride?
Written Questions
1.
Elemental Osmium was first discovered in 1803 as the solid residue left when crude
Platinum was dissolved in Aqua Regia. It is a lustrous blue-white metal that is
currently credited with being the heaviest element; although the measured density is
in doubt and is very close to that of elemental Iridium. X-ray crystallographic
measurements suggest the density of metallic Osmium is 22.661 g/cm3.
a)
What is the mass a cube of this metal, reported in grams, whose sides each
measure 12 inch on each side? (You must show your work!!!)
b)
What is the above result when reported in pounds (lb)? (You must show your
work!!!)
c)
What physical quantity does the unit pound (lb) represent, and are you
bothered by the calculation being asked of you in part (b) above? Provide an
appropriate explanation for your answer.
2.
After strong heating of 2.500g of the Red Calx of Mercury for several days, 2.315g
of elemental Mercury remains.
Red Calx of Mercury
3.
Mercury + Oxygen
a)
How much Oxygen is liberated during this reaction? (You must show your
work!!!)
b)
What is the elemental composition (mass percentage) of the Red Calx of
Mercury? (You must show your work!!!)
Silver has two naturally occurring isotopes. These are 107Ag (106.9051 amu,
51.28%) and 109Ag (108.9047 amu, 48.18%). By direct calculation, determine the
atomic weight of naturally occurring Silver. (You must show your work!!!)
Appendix - Useful Information
Unit Conversions
Common Polyatomic Ions
Ammonium
Cyanide
Hydroxide
Oxalate
Permanganate
CH3CO2or C2H3O2NH4+
CNOHC2O42MnO4-
Nitrate
Nitrite
NO3NO2-
Chromate
Dichromate
CrO42Cr2O72-
Bisulfate
Sulfate
Bisulfite
Sulfite
Thiosulfate
HSO4SO42HSO3SO32S2O32-
Acetate
Bicarbonate
Carbonate
HCO3CO32-
Perchlorate
Chlorate
Chlorite
Hypochlorite
ClO4ClO3ClO2ClO-
Phosphate
PO43Hydrogen Phosphate HPO42Dihydrogen Phosphate H2PO4-
Naming Conventions
(-ide) Endings for the Non-Metals
Group 4A
Carbide
Group 5A
Nitride
Phosphide
Arsenide
Group 6A
Oxide
Sulfide
Selenide
Telluride
Group 7A
Fluoride
Chloride
Bromide
Iodide
Ordering for Non-Metal with Non-Metal Compounds
Element:
Group:
B
3A
Si C Sb As P N
4A
5A
H
Te Se S
6A
Greek Prefixes
Number
one
two
three
four
five
six
seven
eight
nine
ten
Prefix
monoditritetrapentahexaheptaoctanonadeca-
Latin Names of the Elements
English Name
Antimony
Copper
Gold
Iron
Lead
Mercury
Potassium
Silver
Sodium
Tin
Latin Name
Stibium
Cuprum
Aurum
Ferrum
Plumbum
Hydragyrum
Kalium
Argentum
Natrium
Stannum
Symbol
Sb
Cu
Au
Fe
Pb
Hg
K
Ag
Na
Sn
I Br Cl
7A
O F
Fundamental Constants
Mass of Electron = 9.105 x 10-28g
Mass of Proton = 1.6727 x 10-24g
Mass of Neutron = 1.6750 x 10-24g
Fundamental Charge = 1.6022 x 10-19C
Speed of Light = c = 3 x 108 m/sec
Planck's Constant = h = 6.626 x 10-34 J sec
Avogadro's Number = NA = 6.022 x 1023 entities / mole