Final Exam - Spring 2001
Chem. 1021, MWF 11:15-12:05 class (sec. 009)
Prof. Darrin M. York
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1
Formulas/equations
Molar volume at STP (0ÆC=273.15 K, 1 atm) = 22.4 L
temperature conversions: T(F)=(9/5)T(C)+32, T(C)=(5/9)[T(F)-32]
Ideal gas law: P V = nRT
Dalton's law: Ptotal = P1 + P2 + P3 + Hydrogen energy levels:
En =-2.17810 18 J (Z 2 =n2)
En !n =-2.17810 18 J Z 2 (1=n22 1=n21)
photon energy: Ephoton = h = h c/
kinetic theory (rms velocity): urms = (3RT=M )1=2
Enthalpy:PH=E+PV; H=E+(PV);
E = q + w; for PV work: w=-PV
P
Æ
Æ
Hrxn P= npHf (products)P nr HfÆ(reactants) P
H = D(bonds broken) D(bonds formed) where is a sum of terms,
and D is the bond energy per mole of bonds (always positive).
specic heat capacity: E = s m T
Graham's law: (Rate1/Rate2)=(M2 =M1)1=2 Coulomb's law (in J): E=2.3110 19 Jnm Q rQ
Constants
Avogadro's number (NA) = 6:022 1023 mol 1
Ideal gas constant R=0.08206 Latm/Kmol=8.314 J/Kmol
Planck's constant: h=6.62610 34Js
Speed of light: c=2.998108ms 1
1 cm3=1 mL=110 3 L
1 nm = 10 9 m
1 atm = 760 torr
Atomic mass unit (amu): 1 amu = 1.6605410 27 kg = 1 g/mol
electron mass: me =9.1110 31 kg
1
2
1 2
Table 4.1 (Solubility Rules for Salts in Water)
1. Most nitrate (NO3 ) salts are soluble.
2. Most salts containing the alkali metals ions (Li+ , Na+ , K+ , Cs+ , Rb+ ) and the
ammonium ion (NH+
4 ) are soluble.
3. Most chloride, bromide, and iodide salts are soluble. Notable exceptions are salts
containing the ions Ag+ , Pb2+ , and Hg2+
2 .
4. Most sulfate salts are soluble. Notable exceptions are BaSO4 , PbSO4 , Hg2 SO4 ,
and CaSO4 .
5. Most hydroxide salts are only slightly soluble. The important soluble hydroxides
are NaOH and KOH. The compounds Ba(OH)2 , Sr(OH)2 , and Ca(OH)2 are only
marginally soluble.
6. Most sulde (S2 ), cabonate (CO23 ), chromate (CrO24 ), and phosphate (PO34 )
salts are only slightly soluble.
2
MO diagrams for homonuclear diatomic molecules
The unit cell for a nickel arsenide crystal
3
Part I: Material covered on midterm Exam I
1. Which one of the following statements about atomic structure is false?
a) The electrons occupy a very large volume compared to the nucleus.
b) Almost all of the mass of the atom is concentrated in the nucleus.
c) The protons and neutrons in the nucleus are very tightly packed.
d) The number of protons and neutrons is always the same in the
neutral atom.
e) The number of protons plus electrons is always the same in the neutral
atom.
2. An isotope, X , of a particular element has an atomic number of 7 and a mass
number of 15. Therefore,
a) X is an isotope of nitrogen.
b) X has 8 neutrons per atom.
c) X has an atomic mass of 14.0067.
d) a and b
e) a, b and c
3. The reaction of 11.9 g of CHCl3 with excess chlorine produced 12.6 g of CCl4
(carbon tetrachloride) according to:
CHCl3 + Cl2 ! CCl4 + HCl
What is the percent yield?
a) 94.4 %
b) 48.6 %
c) 82.2 %
d) 51.4 %
e) 46.2 %
4
4. Give the correct coeÆcients (w, x, y, z) that balance the following reaction:
wH2 SnCl6 + xH2 S ! y SnS2 + z HCl
a)
b)
c)
d)
e)
w=1, x=2, y=1, z=6
=1, x=2, y=2, z=2
=1, x=1, y=1, z=6
w=6, x=2, y=1, z=1
w=2, x=4, y=2, z=6
w
w
5.
A mixture contained no uorine compound except methyl uoroacetate
(FCH2 COOCH3, molar mass 92.07 g/mol). When chemically treated, all the
uorine was converted to calcium uoride (CaF2 , molar mass 78.07 g/mol). The
mass of CaF2 obtained was 12.1 g. Find the mass of FCH2 COOCH3 in the
original mixture.
a) 92.0 g
b) 28.5 g
c) 24.2 g
d) 14.3 g
e) 12.1 g
6. In the reaction 2H2(g) + O2(g) ! 2H2O(g), O2 is
a) oxidized.
b) reduced.
c) the electron donor.
d) the reducing agent.
e) a and d
5
7. What volume of 2.0 M NaOH is required to neutralize 100 mL of 5.0 M H2SO4 ?
a) 400 mL
b) 500 mL
c) 1 L
d) 2 L
e) none of these
8. Which gas has the highest density (at the same temperature and pressure)?
a) Ne
b) Cl2
c) CH4
d) NH3
e) all the gases have the same density
9. A 4.37-g sample of a certain diatomic gas occupies a volume of 3.00 L at 45ÆC
and 1 atm. Identify the gas.
a) F2
b)
c)
d)
e)
N2
H2
O2
Cl2
10. What volume of carbon dioxide gas measured at STP will be formed by
the reaction of 1.30 mol of oxygen gas with 0.900 mol of ethanol (CH3CH2OH)
according to the reaction:
CH3CH2OH(l) + 3O2(g) ! 2CO2(g) + 3H2 O(g)
a) 8.70 L
b) 19.4 L
c) 28.0 L
d) 40.3 L
e) 91.9 L
6
Part II: Material covered on midterm Exam II
11. A gaseous mixture containing 1.5 mol Ar and 3.5 mol CO2 has a total pressure
of 7.0 atm. What is the partial pressure of CO2?
a) 5.8 atm
b) 6.1 atm
c) 3.0 atm
d) 4.9 atm
e) 2.1 atm
12. At 2400 K, the molecules of an unknown gas X have the same root-meansquare velocity as He gas at 300 K. What is the gas X?
a) Ne
b) Ar
c) H2
d) N2
e) O2
13.
Using the information below, calculate the Hf for PbO(s)
PbO(s) + CO(g) ! Pb(s) + CO2(g) H = -131.4 kJ
Hf for CO2 (g)
-393.5 kJ/mol
Hf for CO(g)
-110.5 kJ/mol
a) -283.0 kJ/mol
b) -262.1 kJ/mol
c) -151.6 kJ/mol
d) -635.4 kJ/mol
e) -372.6 kJ/mol
7
14. How much heat is required to raise the temperature of a 6.21-g sample of
iron [specic heat = 0.450 J/(gÆC)] from 25ÆC to 79.8ÆC?
a) 70.0 J
b) 101 J
c) 386 J
d) 756 J
e) 153 J
15. How many of the following molecules have a permanent dipole moment?
a) 0
b) 1
SF2, NH3, CCl4, PCl5
c) 2
d) 3
e) 4
16. Which of the following exhibits the correct orders for both increasing atomic
radius and increasing electronegativity, respectively?
a) radius: S < O < F, and electronegativity: S < O < F
b) radius: F < S < O, and electronegativity: O < S < F
c) radius: S < F < O, and electronegativity: S < F < O
d) radius: F < O < S, and electronegativity: S < O < F
e) none of these
8
17. The electron conguration of Ti2+ is:
a) [Ar]4s2
b) [Ar]4s1 3d1
c) [Ar]3d2
d) [Ar]4s2 3d2
e) none of these
18. Which of the following statements about quantum theory is incorrect?
a) There is a fundamental limitation as to to how precisely we can know both
the position and momentum of an electron simultaneously.
b) Lower energy orbitals are lled with electrons before higher energy orbitals.
c) When lling orbitals of equal energy, two electrons will occupy
the same orbital with paired spins before lling a new orbital.
d) No two electrons in the same atom can have the same four quantum numbers.
e) All of these are correct.
19. Which of the following combinations of quantum numbers (n, l, m and ms)
is not allowed?
a) n=1, l=1, m=0, ms =1/2
b)
c)
d)
e)
n=3, l=0, m=0, ms =-1/2
n=2, l=1, m=-1, ms =1/2
n=4, l=3, m=-2, ms =-1/2
n=4, l=2, m=0, ms =1/2
20. In the hydrogen spectrum, what is the wavelength of light associated with
the n = 3 ! n = 2 electronic transition?
a) 12.67 nm
b) 547.2 nm
c) 91.22 nm
d) 121.6 nm
e) 656.7 nm
9
Part III: Material covered on midterm Exam III
21. Given the following bond energies:
C | C 347 kJ/mol
C = C 614 kJ/mol
C | O 358 kJ/mol
C = O 799 kJ/mol
C | H 413 kJ/mol
O | H 467 kJ/mol
O | O 146 kJ/mol
estimate the H for the reaction (Note: H2 O2 is H-O-O-H):
H2 O2 + CH3OH ! H2 CO + 2H2 O
a) -349 kJ
b) -585 kJ
c) -544 kJ
d) +585 kJ
e) +349 kJ
22. Select the correct molecular structure for ICl4
a) square pyramidal
b) tetrahedral
c) square planar
d) see-saw
e) octahedral
23. Select the correct molecular structure for SO23
a) trigonal pyramidal
b)
c)
d)
e)
trigonal planar
T-shaped
trigonal bipyramidal
octahedral
10
24.
Calculate the lattice energy for NaF(s) given the following information:
sublimation energy for Na(s) +109 kJ/mol
Hf for F(g)
+77 kJ/mol
rst ionization energy of Na(g) +495 kJ/mol
electron aÆnity of F(g)
-328 kJ/mol
Hf for NaF(s)
-570 kJ/mol
a) -217 kJ/mol
b) -923 kJ/mol
c) -1047 kJ/mol
d) -3916 kJ/mol
e) none of these
25. What is the formal charge on boron in the H3N-BF3 molecule?
a) -2
b) -1
c) 0
d) 1
e) 2
26. For how many of the following does the bond order decrease if you take away
one electron from the neutral molecule (refer to the MO diagram on inside page)?
B2 , C2, N2 , F2
a) 0
b) 1
c) 2
d) 3
e) 4
11
27. The hybridization of xenon in XeF4 is
a) sp2
b) sp3
c) sp4
d) dsp3
e) d2 sp3
28. The molecule CH3 C CCH2CH2Cl is named:
a) 1-chloro-3-pentyne
b) 5-chloro-2-pentene
c) 1-acetylenyl-3-chloropropane
d) 5-chloro-2-pentyne
e) 1-chloro-3-pentene
29. How many isomers of C2 Cl2 Br2 are there?
a) 1
b) 2
c) 3
d) 4
e) 5
30. Of the series of diatomic molecules:
O2 , O2 , O+2, O2+
2
which paramagnetic molecule has the shortest O-O bond length (refer to the MO
diagram on inside page)?
a) O2
b) O2
c) O+2
d) O2+
2
e) none are paramagnetic
12
Part IV: Material from the last part of the class (after Exam III)
31. The boiling point of methanol is much higher than that of ethane. This is
primarily due to
a) Strong London dispersion forces in methanol.
b) Hydrogen bonding in methanol.
c) Long-ranged ion-ion forces in methanol.
d) The carbon-oxygen double bond in the methanol.
e) none of these
32. Identify the type of organic compound shown:
CH3 |
CH | CH3
j
NH2
a) nitrocarbon
b) primary amine
c) secondary amine
d) tertiary amine
e) none of these
33. Identify all the functional groups present in the following organic compound:
1) ketone, 2) aldehyde, 3) carboxylic acid, 4) ether, 5) ester, 6) alcohol
O
O
k
k
CH3 C | O | CH2CH2COH
a) 2,6
b) 1,4,6
c) 1,3,4
d) 3,5
e) 1,5,6
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34. Small molecules such as water are formed with the extension of the polymer
chain in which kind of polymerization reaction?
a) crosslinking
b) condensation
c) addition
d) substitution
e) vulcanization
35. What monomer(s) is (are) needed to produce the below polymer?
CH3
CH3
CH3
j
j
j
|(| C | CH2 | C | CH2 | C | CH2 |)n|
j
j
j
CH3
CH3
CH3
a) CH2 = CH2 and CH3CH = CH2
b) CH2 = C(CH3 )2
c) CH3 CH = CHCH3
d) CO and CH2 = CH2
e) none of the above
36. Name the following compound
Cl
O
j
k
CH3 | CH | CH | C | CH(CH3)2
j
CH2
j
CH3
a) 2-chloro-3-ethyl-1-isopropylbutanone
b) 3-chloro-2-ethyl-5-methyl-4-hexanone
c) 2-butyl,chloro,isobutyl methane
d) 4-chloro-2,5-dimethyl-3-heptanone
e) 3-methyl-4-chloro-1-isopropylpentanone
14
37. Which one of the following decreases as the strength of the attractive intermolecular forces increases?
a) The heat of vaporization.
b) The normal boiling temperature.
c) The extent of deviations from the ideal gas law.
d) The surface tension of a liquid.
e) The vapor pressure of a liquid.
38. Which of the following statements is true about a p-type silicon semiconductor?
a) It is produced by doping Si with P or As.
b) Electrons are the mobile charge carriers.
c) It does not conduct electricity as well as pure Si.
d) All are true.
e) None is true.
39. A metal is typically characterized by:
I. EÆcient conduction of heat and electric current.
II. A large energy gap between the lled MOs of the metal and the empty
MOs that form the conduction band.
III. Nondirectional covalent bonding involving highly delocalized electrons.
a) I
b) II
c) III
d) I and III
e) I, II and III
40.
The unit cell for a nickel arsenide crystal is shown on the inside page. What
is the empirical formula for the compound?
a) NiAs
b)
c)
d)
e)
Ni2 As
Ni3 As
Ni6 As2
NiAs2
15