Foothill College
Chem25 Exam2A
Nov. 18, 2009
Name:
Constants/Conversions
atm = 101.325 J
1 J = 107 erg
RH = 2.18 x 10-18 J
1 eV = 96.45 kJ/mol 1atm = 760 torr = 760 mm-Hg = 1.01325 x105 Pa
Equations
E = hv C= vλ
K = °C + 273.15
ΔT = kfm
En = (-RH)
π = MRT
λ = h/mv
ΔE = q + w
Ecell = Ered + Eox
q = CΔT = n CΔT = m s ΔT
E = hc/λ
EΨ = HΨ
ΔT= kbm
1
n2
Specific Heat =
R1/R2 = (M1/M2)-1/2
Ln A = ln A0 -kt
KP = KC (RT)Δn
F = 96,485 Coul/mol
pH = pKa + log(
[base]
)
[acid]
C=3.00 x 108 m/s
e =1.602 x 10-19 Coul
1 amu= 1.66054 x 10-24 g
NA = 6.02214 x 1023
h = 6.626 x 10-34 JS
R = 8.3145 J/K°mol
= 0.082058 L atm/ K°mol
k = 1.38066 x 1023 J/K°
1 Cal = 4.184 J
1L
q
m ⋅ ΔT
ln (
ΔH Vap
P1
)=P2
R
⎛1
1 ⎞
⋅ ⎜⎜ − ⎟⎟
⎝ T1 T2 ⎠
E ∝ (Q+ Q)/d
t1/2 = 0.693/k
KaKb = Kw = 1 x 10-14
Cu2+ + 2e- → Cu(S)
nλ = 2d⋅sinθ ΔG = ΔH -TΔS
k = A⋅exp(-Ea/RT)
1/A = 1/A0 -kt
E° = + 0.337
ΔG = ΔG° =RT⋅ ln (Q)
E = E° -
ΔS°rxn = ΣnΔSf°(products) - ΣmΔSf°(reactants)
ΔH°rxn = ΣnΔH°f(product)-ΣnΔH°(reactant)
2.303 ⋅ RT
⋅log (Q)
nF
ΔG = -nFE
P1 = χ1PTotal
1A
8A
1
1
2
3
4
5
6
7
2
H
1.008 2A
3
4
Li
Be
Na
Mg
K
Ca
Rb
3A
5
6.941 9.012
11
12
4A
6
5A
7
6A
8
He
7A
4.003
10
9
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
10.81 12.01 14.01 16.00 19.00 20.18
13
14
15
16
17
18
22.99 24.31
3B
19
20
21
4B
22
5B
23
6B
24
7B
25
Sc
Ti
V
Cr
Mn
Sr
Y
Zr
Nb
Mo
Tc
Cs
Ba
La
Hf
Ta
W
Re
Fr
Ra
Ac
Rf
Ha
Sg
Ns
26
8B
27
28
1B
29
2B
30
26.98 28.09 30.97 32.07 35.45 39.95
31
32
33
34
35
36
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Hs
Mt
39.10 40.08 44.96 47.90 50.94 52.00 54.94 55.85 58.93 58.70 63.55 65.39 69.72 72.59 74.92 78.96 79.90 83.80
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
85.47 87.62 88.91 91.22 92.91 95.94 (98)
55
56
57
72
73
74
75
101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3
76
77
78
79
80
81
82
83
84
85
86
132.9 137.3 138.9 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210)
87
88
89
104
105
106
107
108
109
110
111
(223) (226)
(227) (261) (262) (266) (262)
58
6
7
59
60
61
Ce
Pr
Nd
Pm
Th
Pa
U
Np
Rn
(222)
(265) (266)
62
63
64
65
66
Sm
Eu
Gd
Tb
Dy
Pu
Am
Cm
Bk
Cf
67
68
69
70
71
Ho
Er
Tm
Yb
Lu
Es
Fm
Md
No
Lw
140.1 140.9 144.2 (145) 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0
90
91
92
93
94
95
96
97
98
99
100
101
102
103
232.0 (231) 238.0 (244)
(242) (243) (247) (247) (251)
(252) (257) (258) (259) (260)
1
Foothill College
Chem25 Exam2A
Nov. 18, 2009
Name:
molecule
CH4(g)
HCl(g)
CHCl3(l)
HF(g)
CH3OH(l)
CO(g)
HNO3(l)
CO2(g)
H2O(g)
H2O(l)
ΔHf˚
-74.8
-92.3
-131.8
-268.6
-238.6
-110.5
-173.2
-393.5
-241.8
-285.8
2
Foothill College
Chem25 Exam2A
Nov. 18, 2009
Name:
MULTIPLE CHOICE QUESTIONS (60)
0. Your Section number is
A. 01 (Monday Lab)
B. 02 (Wednesday Lab)
1. Which statement about boiling point is FALSE?
A. The boiling point is higher for compounds with strong intermolecular forces.
B. The boiling point is higher for compounds with a high viscosity.
C. The boiling point of a compound is an absolute constant.
D. The boiling point of a compound is higher for nonvolatile compounds.
2.
Increasing the intermolecular forces of a liquid will do which of the following?
A. increase the viscosity
B. decrease the evaporation rate
C. decrease the vapor pressure
D. all of the above
3. The rate of vaporization of a liquid can be increased by
1. increasing the surface area
2. increasing the temperature
3. decreasing the strength of the intermolecular forces
A. 1 only
B. 2 only
C. 3 only
D. 1 and 2 only
4. What happens as you start to add heat to a solid substance?
A. Thermal energy causes the components of the solid to vibrate faster in their stationary position.
B. When the melting point is reached, the thermal energy is sufficient to overcome intermolecular
forces holding the components stationary.
C. Heating of the now formed liquid results in increasing the liquid temperature.
D. all of the above
5. Which statement is true in describing what occurs when a solid melts to a liquid?
A. The process is endothermic and the heat of fusion is positive.
B. The process is endothermic and the heat of fusion is negative.
C. The process is exothermic and the heat of fusion is positive.
D. The process is exothermic and the heat of fusion is negative.
6. Which noble gas has the highest boiling point?
A. Ne
B. Ar
C. Kr
D. Xe
7. Substance A is a molecular compound that dissolves in gasoline but not in water. The molecules of A are
very likely:
A. metallic.
B. nonmetallic.
C. polar.
D. nonpolar.
3
Foothill College
Chem25 Exam2A
Nov. 18, 2009
Name:
8. The primary cause of increasing greenhouse gases is:
A. the burning of vast amounts of rain forests.
B. the production of CO2 by respiration.
C. the increased use of natural gas, petroleum and coal.
D. the release of CO2 by decreasing solubility in the ocean.
9. How many grams of water are made from the reaction of 4.0 grams of hydrogen gas?
Given the reaction: 2H 2 + O 2 → 2H 2 O
A. 18
B. 72
C. 36
D. 4.5
10. What is the limiting reactant for the following reaction given we have 2.6 moles of HCl and 1.4 moles of
Ca(OH) 2?
2HCl + Ca(OH) 2 → 2H 2 O + CaCl2
A. Ca(OH)2
B. HCl
C. H2O
D. CaCl2
11. A sample of 8.5 g NH3 on oxidation produces 4.5 g of NO. Calculate the percent yield.
A.
B.
C.
D.
15 %
30%
60%
70%
12. What type of a reaction occurs when a potassium nitrate solution is mixed with a barium acetate
solution?
A. precipitation
B. acid-base neutralization
C. gas evolution
D. no reaction
13. Given that 4 NH3 + 5 O2 → ? NO + 6 H2O, when 4.50 mol of H2O are formed, the amount of NO formed
is
A. 1.50 mol
B. 3.00 mol
C. 4.50 mol
D. 6.75 mol
14. What is the gas produced when hydrochloric acid is reacted with ammonium carbonate?
A. ammonia
B. chlorine
C. hydrogen
D. carbon dioxide
4
Foothill College
Chem25 Exam2A
15. Considering the following reaction:
Nov. 18, 2009
Name:
Pb(NO3 ) 2 ( aq ) + 2KI ( aq ) → PbI 2 ( s ) + 2KNO3 ( aq )
Which
ion(s) would be spectator ions?
A. Pb2+, NO3B. K+, NO3C. K+, ID. Pb2+, K+
16. A precipitate is expected to be formed when an aqueous solution of sodium sulfate is added to an
aqueous solution of
A. iron(III) chloride
B. potassium chloride
C. magnesium chloride
D. barium chloride
17. When elements combine to form compounds,
A. their properties are an average of all elements in the compound.
B. their properties change completely.
C. their properties do not change.
D. their properties are completely random.
18. Which of the following compounds have the smallest formula mass?
A. CO2
B. NO2
C. SiO2
D. H2O
19. You have 10.0 g each of Na, C, Pb, Cu and Ne. Which contains the largest number of moles?
A. Na
B. C
C. Pb
D. Ne
20. Which of the following molecules contain 9.02 × 1023 atoms?
A. 4.00 g H2
B. 9.00 g H2O
C. 28.0 g N2
D. 32.0 g O2
SHORT ANSWER (20 pts)
1. Definition. (5 pts)
A. Normal boiling point
B. Dispersion forces
C. Oxidation-reduction reactions
D. Spectator ions
E. Empirical
2. Nomenclatures
A. Mgnesium phosphate
B. Barium nitrite
C. Fe3(PO4)2
D. SF5
E. HBrO
5
Foothill College
Chem25 Exam2A
Nov. 18, 2009
Name:
3. How many kilojoules of heat are needed to completely vaporize 42.8grams of C 4 H 10 O at its
boiling point? (ΔHvap = a kJ/mol on the white board)
[(42.8 g)/(74.12 g/mol)] x (a kJ/mol) = 0.577a kJ
4. Evidences of a chemical reaction occur.
LONG ANSWER （10 pts each）
1. What is the limiting reactant, theoretical yield, and percent yield for the following reaction given we
have 557.899 g of Ca(NO3)2, 611.236 of Li3PO4 and 351.543 g of calcium phosphate produced? (you
must write a balanced chemical equation)
3Ca(NO3 ) 2 + 2Li3PO 4 → 6LiNO3 + Ca 3 (PO 4 ) 2
3Ca(NO3)2
+
2Li3PO4
→
6LiNO3
+
MM
164.088
115.79
68.948
mass
557.899
611.236
mole
3.400 1.5 pts
5.2788 1.5 pts
mole/coef.
1.133 1.5 pts
2.639 1.5 pts
LR 1 pt
1 pt
1.5 pts
AY= 351.543
PY=
(AY/TY)x100% = 100.00
1.5 pts
Ca3(PO4)2 1.5 pts
310.188
1.133 1.5 pts
351.546 1.5 pts
TY
2. A compound contains 13.58 g of carbon, 1.76 g of hydrogen and 13.45 g of oxygen.
mass of 180.15 g/mol. What is its molecular formula?
Mass
C
H
O
Molar mass 180.15
Formula weight
13.58
1.76
13.45
102.088
mole
mole ratio
n
1.1307
1.35
3
1.7460
2.08
3
0.8406
1.00
3
1 pt
1 pt
n=
1 pt
It has a molar
E. F.
4
6
3
1 pts
M. F.
C8
H12
O6
1 pt
2 1 pt
6