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CHEM 10050
Fall 1995
Exam #2
Name ________________________
Soc. Sec.# ____________________
Multiple Choice (3 pts. each)
____ 1) How many moles of K3PO4 are 21.2 g K3PO4?
a) 1.00
b) 0.100
c) 0.158
d) 0.129
____ 2) The correct formula for potassium permanganate is:
a) K2MnO4
b) K2Cr2O7
c) KMnO4
d) KCr2O7
____ 3) 9.0 g of water contains:
a) 3.0 x 1023 molecules
c) 6.022 x 1023 molecules
b) 3.0 x 1023 atoms
d) 6.022 x 1023 atoms
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____ 4) The sulfur atom in the ion SO 3 has an oxidation number of:
a) -2
b) -4
c) +2
d) +4
____ 5) The following reaction is a _____________ reaction: CaO + H 2O  Ca(OH)2.
a) combination
b) decomposition
c) single displacement
d) combustion
____ 6) The oxidation number of the nitrogen atom in potassium nitrite is:
a) +3
b) +4
c) +5
d) +6
____ 7) The energy required to remove and electron from an atom is called:
a) electronegativity
b) ionization energy
c) electron affinity
d) polarity
c) electronegative
d) polar
____ 8) The oxygen difluoride (OF2) molecule is:
a) tetrahedral
b) non-polar
____ 9) The formula for copper (II) sulfate is:
a) Cu(SO4)2
b) Cu2SO4
c) Cu3SO4
d) CuSO4
____ 10) The reaction between an acid and a base produces:
a) carbon dioxide and salt
c) water and salt
b) carbon monoxide and water
d) carbon dioxide and water
____ 11) In which compound does nitrogen have an oxidation state of +5?
a) KNO2
b) Ba(NO3)2
c) N2H4
d) NH3
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____ 12) Oxygen in most of its compounds has an oxidation number of:
a) +1
b) +2
c) -1
d) -2
____ 13) During the formation of an ionic bond, the atom which transfers its valence
electron(s) to the other atom is the atom with the:
a) higher electronegativity
c) higher ionization energy
b) lower electronegativity
d) no correct answer given
____ 14) How many grams of gold (Au) are in 0.275 mol Au?
a) 0.542 g
b) 5.42 g
c) 54.2 g
d) 542. g
c) Al(OH)3
d) Al3OH
____ 15) The correct formula for aluminum hydroxide is:
a) AlOH
b) Al2(OH)3
____ 16) The attractive force that an element has for electrons shared in a covalent bond is
called:
a) electronegativity
b) ionization energy
c) electron affinity
d) polarity
____ 17) The bond in LiBr is:
a) polar covalent
b) interesting
c) ionic
d) non-polar covalent
____ 18) Given the following unbalanced equation: H2 + O2  H2O
How many moles of oxygen is required to produce 3.6 g of H2O?
a) 0.100 mol
b) 1.00 mol
c) 10.0 mol
d) 100 mol
____ 19) A molecule that is electrically unsymmetrical and is oppositely charged at two
points within the molecule is called:
a) a dipole
b) impossible
c) ionic
d) covalent
____ 20) The percentage composition for the molecule C7H8O:
a) 91.30 % C, 6.63 % H, 2.07 % O
c) 77.75 % C, 7.46 % H, 14.8 % O
b) 67.74% C, 6.45 % H, 25.81 % O
d) 41.39 % C, 3.47 % H, 35.13 % O
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Solve the following problems showing all work.
significant figures and rounding.
Remember to use proper units,
1) Balance the following equations and write total ionic and net ionic equations for each.
Circle the spectator ions in the total ionic equation (8 pts.)
a) HNO3(aq) + Na2CO3(aq)  H2O(l) + CO2(g) + NaNO3(aq)
b) Pb(NO3)2(aq) + K2Cr2O7(aq)  PbCr2O7(s) + KNO3(aq)
2) Given the following unbalance equation, CO + H2  CH3OH, complete the following
(20 pts.):
a) Write the balance equation
b) How many milliliters of methyl alcohol (CH3OH) would be produced from 2.50 g of
hydrogen gas (dCH3OH = 0.792 g/mL)?
c) If 15.0 mL of CH3OH is actually collected by the person doing this reaction, what is
the percentage yield?
d) What class of reaction does this represent?
e) Is this a redox reaction? If it is, indicate which reactant is the oxidizing agent and
which reactant is the reducing agent.
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4) Draw Lewis Structures and predict the molecular geometry’s for the following (12 pts.):
a) SiBr4
b) SeO2
c) N3
d) Circle the polar molecule above.