Chemistry 1412
Chapter 12
Homework
1) Which of the following concentration unit will be affected by temperature?
(a) Mass percent
(b) mole fraction
(c) molarity (d) molality (e) ppm
2) Which of the following action will reduce the solubility of a gas in water?
(a) Pressure (b) temperature (c) molar mass of the gas (d) acidic or basic gas
3) A 0.270 M KOH solution has a density of 1.01 g/mL. Calculate the molality (m)
of KOH. (a) 0.271 (b) 0.273 (c) 0.265
(d) 0.267
4) Which of the following pair is miscible (i.e. soluble to each other)?
(a) CH3OH and C6H6 (b) CCl4 and H2O (c) C6H12O6 and C2H5OH
(d) CH3Cl and CH3COOH
5) What’s the concentration if the osmotic pressure for sucrose, C12H22O11, solution
is 0.048 atm at 20oC?
(A)1.9M
(B)0.25 M (C) 0.002M
(D)2
6) The osmotic pressure of 0.050 M MgSO4 at 25
Van't Hoff factor?
(A)1.9
(B)1.3 (C)2.5
(D)2
C is 1.60 atm. What is the
7) What mass of sucrose (C12H22O11) in kilograms must be added to 552 g of
water to yield a solution with vapor pressure 2.0 mmHg less than that of pure water
at 20 °C (The vapor pressure of water is 17.5 mmHg at 20 °C)?
A)
0.52 kg B) 0.052 kg C) 1.3 kg
D) 3.1 kg
8) Which of the following has very high solubility in water?
A)
C6H6
B)C2H5OH C) C6H5NH2
D) C6H5OH
9) Which of the following is more soluble in benzene than in water?
A)
potassium chloride
B)
naphthalene
C)
washing soda
D)
CsF
10) 12 g of urea (molar mass = 60 g) is dissolved in 180 g of water. The mole
fraction of urea is :
A)
0.20
B)
0.066
C)
0.020
D)
0.66
11) 6.00 g of urea (molar mass = 60 g) is dissolved in 100 g of water (M.W – 18).
The percent by mass of urea in the solution is _____.
A)
5.7%
B)
6.0%
C)
16.6%
D)
3.0%
12) The molality of 14.3 g of sucrose (C12H22O11) in 676 g of water is _____.
A)
0.0210 m
B)
2.03 m
C)
0.0619 m
D)
1.09 m
13) What is the molality of a 5.86 M ethanol (C2H5OH) solution whose density is
0.927 g/mL?
A)
1.53 m
B)
0.68 m
C)
1.68 m
D)
8.92 m
14) The molality of a 48.2% by mass of KBr solution is _____.
A)
3.42 m
B)
7.82 m
C)
5.12 m
D)
10.08 m
15) The boiling point of a 2.47 m naphthalene in benzene solution (b.p 80.1◦C ) is:
(Kb=2.53◦C/m)
A)
86.3 ◦C
B)
82.1 ◦C
C)
83.7 ◦C
D)
84.5 ◦C
16) An aqueous solution of a nonelectrolyte freezes at –1.1 ◦C. The molality of the
solution is (Kf=1.86◦C/m).
A)
0.49 m
B)
0.035 m
C)
0.59 m
D)
1.26 m
17)The freezing point of 21.2 g of NaCl in 135 mL of water(Kf=1.86◦C/m) is
_____.
A)
–5.00 ◦C
B)
–4.60 ◦C
C)
–9.99 ◦C
18) A solution of 12.00 g of an unknown non dissociating compound dissolved in
200.0 g of benzene freezes at 3.45oC. The Kf of benzene is 5.07oC/m. The freezing
point of benzene is 5.45oC.
(a) What is the mass percent of the solution?
(b) What is the molality of the unknown solution?
(c) How many moles of unknown in the solution?
(d) What is the molar mass of the unknown?
(e) Assume the density of the unknown solution is 1.35 g/mL, what is the molarity
of the unknown solution?