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CHEM 10050Exam #2Name ______
Fall 1995Soc. Sec.# ______
Multiple Choice (3 pts. each)
____1) How many moles of K3PO4 are 21.2 g K3PO4?
a) 1.00b) 0.100c) 0.158d) 0.129
____2) The correct formula for potassium permanganate is:
a) K2MnO4b) K2Cr2O7c) KMnO4d) KCr2O7
____3) 9.0 g of water contains:
a) 3.0 x 1023 moleculesb) 3.0 x 1023 atoms
c) 6.022 x 1023 moleculesd) 6.022 x 1023 atoms
____4) The sulfur atom in the ion SOhas an oxidation number of:
a) -2b) -4c) +2d) +4
____5) The following reaction is a ______reaction: CaO + H2O Ca(OH)2.
a) combinationb) decompositionc) single displacementd) combustion
____6) The oxidation number of the nitrogen atom in potassium nitrite is:
a) +3b) +4c) +5d) +6
____7) The energy required to remove and electron from an atom is called:
a) electronegativityb) ionization energyc) electron affinityd) polarity
____8) The oxygen difluoride (OF2) molecule is:
a) tetrahedral b) non-polarc) electronegatived) polar
____9) The formula for copper (II) sulfate is:
a) Cu(SO4)2b) Cu2SO4c) Cu3SO4d) CuSO4
____10) The reaction between an acid and a base produces:
a) carbon dioxide and saltb) carbon monoxide and water
c) water and saltd) carbon dioxide and water
____11) In which compound does nitrogen have an oxidation state of +5?
a) KNO2b) Ba(NO3)2c) N2H4d) NH3
____12) Oxygen in most of its compounds has an oxidation number of:
a) +1b) +2c) -1d) -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 electronegativityb) lower electronegativity
c) higher ionization energyd) no correct answer given
____14) How many grams of gold (Au) are in 0.275 mol Au?
a) 0.542 gb) 5.42 gc) 54.2 gd) 542. g
____15) The correct formula for aluminum hydroxide is:
a) AlOHb) Al2(OH)3c) Al(OH)3d) Al3OH
____16) The attractive force that an element has for electrons shared in a covalent bond is called:
a) electronegativityb) ionization energyc) electron affinityd) polarity
____17) The bond in LiBr is:
a) polar covalentb) interestingc) ionicd) 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 molb) 1.00 molc) 10.0 mold) 100 mol
____19) A molecule that is electrically unsymmetrical and is oppositely charged at two points within the molecule is called:
a) a dipoleb) impossiblec) ionicd) covalent
____20) The percentage composition for the molecule C7H8O:
a) 91.30 % C, 6.63 % H, 2.07 % Ob) 67.74% C, 6.45 % H, 25.81 % O
c) 77.75 % C, 7.46 % H, 14.8 % Od) 41.39 % C, 3.47 % H, 35.13 % O
Solve the following problems showing all work. Remember to use proper units, significant figures and rounding.
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.
4) Draw Lewis Structures and predict the molecular geometry’s for the following (12 pts.):
a) SiBr4
b) SeO2
c) N
d) Circle the polar molecule above.