Sabtu, 01 Agustus 2009

CONCENTRATION OF SOLUTION: MOLALITY AND MOLE FRACTION

1.The density of a 56.0% by weight aqueous solution of methanol (CH3OH) is 0.9046 g/cm3. What is the molality of the compound? (Ar: C = 12, H = 1, O = 16).
a) 36.8
b) 39.7
c) 37.9
d) 40.9
e) 38.6
2.The density of a 72.0% by weight aqueous solution of ethanol (CH3CH2OH) is 0.8644 g/cm3. What is the molality of the compound? (Ar: C = 12, H = 1, O = 16).
a) 58.9
b) 55.8
c) 57.2
d) 53.0
e) 54.1
3.Concentrated HBr is 48.0% HBr by mass and has a density of 1.50 g/mL. What is the molality of this solution? (Ar: H = 1, Br = 80).
a) 12.5
b) 11.4
c) 12.2
d) 11.6
e) 11.9
4.What is the molality of a solution of 25 g of ethyl alcohol (C2H5OH) in 200.0 mL of benzene, C6H6? The density of benzene is 0.879 g/mL. (Ar: C = 12, H = 1, O = 16).
a) 4.5
b) 0.31
c) 3.1
d) 0.62
e) 0.45
5.What is the molality of a solution of 50.0 g of methyl alcohol, CH3OH, in 450.0 g of water? (Ar: C = 12, H = 1, O = 16).
a) 0.700
b) 1.73
c) 3.47
d) 0.173
e) 0.347
6.Formalin is a preservative solution used in biology laboratories. It contains 40 cm3 of formaldehyde, CH2O, (density 0.82 g/cm3) per 100 cm3 of water. What is the molality of formalin? (Ar: C = 12, H = 1, O = 16).
a) 10
b) 8.0
c) 11
d) 12
e) 9.0
7.The density of a 3.29 M aqueous solution of (NH4)2SO4 is 1.2077 g/cm3. What is the molality of the solution? (Ar: N = 14, S = 32, O = 16, H = 1).
a) 3.60
b) 4.26
c) 3.29
d) 3.82
e) 4.03
8.A solution of vinegar is 0.763 M in acetic acid, C2H4O2. The density of vinegar is 1.004 g/mL. What is the molal concentration of acetic acid?
(Ar: C = 12, H = 1, O = 16).
a) 0.751
b) 0.796
c) 0.715
d) 0.815
e) 0.730
9.The density of a 0.872 M aqueous solution of K2CrO4 is 1.129 g/cm3? What is the molality of the solution? (Ar: K = 39, Cr = 52, O = 16).
a) 0.872
b) 0.909
c) 0.232
d) 1.50
e) 0.0909
10.What is the molality of a CsCl solution with a mole fraction of 0.0967? (Ar: Cs = 133, Cl = 35.5, H = 1, O = 16).
a) 5.29
b) 5.55
c) 5.73
d) 5.95
e) 6.21
11.What is the molality of a K2CrO4 solution with a mole fraction of 0.0161? (Ar: K = 39, Cr = 52, O = 16, H = 1).
a) 0.841
b) 0.790
c) 0.820
d) 0.909
e) 0.872
12.What is the molality of a CH3OH solution with a mole fraction of 0.417? (Ar: C = 12, H = 1, O = 16).
a) 35.8
b) 37.3
c) 38.2
d) 39.7
e) 36.4
13.What is the mole fraction of CsCl in a solution prepared from 0.297 moles of CsCl and 2.78 moles of water? (Ar: Cs = 133, Cl = 35.5, H = 1, O = 16).
a) 0.105
b) 0.116
c) 0.0912
d) 0.0861
e) 0.0967
14.What is the mole fraction of CH3CH2CH2OH in a solution prepared from 0.932 moles of CH3CH2CH2OH and 2.44 moles of water? (Ar: C = 12, H = 1, O = 16).
a) 0.258
b) 0.241
c) 0.292
d) 0.227
e) 0.276
15.What is the mole fraction of Pb(NO3)2 in a solution prepared from 0.0543 moles of Pb(NO3)2 and 4.55 moles of water? (Ar: Pb = 207, N = 14, O = 16).
a) 0.129
b) 0.0129
c) 0.136
d) 0.0136
e) 0.0118
16.An automobile antifreeze solution contains 2.42 kg of ethylene glycol, HOCH2CH2OH, and 2.00 kg of water. What is the mole fraction of ethylene glycol? (Ar: C = 12, H = 1, O = 16).
a) 0.290
b) 0.710
c) 0.260
d) 0.320
e) 0.740
17.What is the mole fraction of ethanol, C2H5OH in an alcoholic beverage that is 40% ethanol and 60% water by weight? (Ar: C = 12, H = 1, O = 16).
a) 0.39
b) 0.29
c) 0.21
d) 0.71
e) 0.79
18.What is the mole fraction of C6H5OH in a solution containing 23.5 g of C6H5OH and 41.4 g of C2H5OH? (Ar: C = 12, O = 16, H = 1).
a) 0.200
b) 0.262
c) 0.217
d) 0.231
e) 0.299
19.Sterling silver contains 92.5% silver and 7.5% copper by weight. What is the mole fraction of silver? (Ar: Ag = 108, Cu = 63.5).
a) 0.88
b) 0.93
c) 0.81
d) 0.85
e) 0.94
20.Nichrome contains 80.0% nickel and 20.0% chromium by weight. What is the mole fraction of chromium? (Ar: Ni = 59, Cr = 52).
a) 0.220
b) 0.200
c) 0.160
d) 0.180
e) 0.240
21.A coin contains 90.0% silver and 10.0% copper by weight. What is the mole fraction of copper? (Ar: Ag = 108, Cu = 63.5).
a) 0.158
b) 0.115
c) 0.129
d) 0.100
e) 0.141
22.Naval brass contains 60.0% copper, 39.0% zinc and 1.0% tin by weight. What is the mole fraction of zinc? (Ar: Cu = 63.5, Zn = 65.4, Sn = 119).
a) 0.374
b) 0.385
c) 0.360
d) 0.348
e) 0.398
23.Type metal contains 82.0% lead, 15.0% antimony and 3.0% copper by weight. What is the mole fraction of copper? (Ar: Pb = 207, Sb = 122, Cu = 63.5).
a) 0.056
b) 0.083
c) 0.030
d) 0.043
e) 0.069
24.Babbitt metal contains 90.0% tin, 7.0% antimony, and 3.0 carbon by weight. What is the mole fraction of antimony? (Ar: Sn = 119, Sb = 122, C = 12).
a) 0.071
b) 0.054
c) 0.062
d) 0.045
e) 0.030
25.Babbitt metal is 69.0% zinc, 19.0% tin, 4.0% copper, 3.0% antimony and 5.0% lead by weight. What is the mole fraction of tin? (Ar: Zn = 65.4, Sn = 119, Cu = 63.5, Sb = 122, Pb = 207).
a) 0.152
b) 0.121
c) 0.190
d) 0.109
e) 0.132
26.Pewter contains 85.0% tin, 6.8% copper, 6.5% bismuth and 1.7% antimony by weight. What is the mole fraction of copper? (Ar: Sn = 119, Cu = 63.5, Bi = 209, Sb = 122).
a) 0.10
b) 0.12
c) 0.080
d) 0.068
e) 0.14
27.Pewter contains 85.0% tin, 6.8% copper, 6.5% bismuth and 1.7% antimony by weight. What is the mole fraction of bismuth? (Ar: Sn = 119, Cu = 63.5, Bi = 209, Sb = 122).
a) 0.051
b) 0.036
c) 0.059
d) 0.065
e) 0.045
28.A 10.0% by mass solution of ethanol, C2H5OH, in water has a density of 0.983 g/cm3 at 15oC. What is the mole fraction of ethanol? (Ar: C = 12, H = 1, O = 16).
a) 0.042
b) 0.065
c) 0.06
d) 0.04
e) 0.05
29.The density of a 48.0% by weight aqueous solution of H2SO4 is 1.38 g/cm3. What is the mole fraction of the compound? (Ar: H = 1, S = 32, O = 16).
a) 0.145
b) 0.178
c) 0.165
d) 0.131
e) 0.157
30.The density of a 28.0% by weight aqueous solution of H3PO4 is 1.1686 g/cm3. What is the mole fraction of the compound? (Ar: H = 1, O = 16, P = 31).
a) 0.067
b) 0.076
c) 0.072
d) 0.062
e) 0.069

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