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‫بسم هللا الرحمن الرحيم‬
The Islamic University of Gaza
Faculty of Science
Chemistry Department
Chem for Eng.
final Exam 19.8.2004
Time : 2 hours
Name ……………………………………………….Student Number. …………….
1) Indicate if the following statements are true (√ ) or false (X) (8 points)
(
(
(
(
(
(
(
(
)
)
)
)
)
)
)
)
1 – A mixture of a gas in a gas can only form a solution
2 – Enthalpy is the heat of reaction at constant pressure
3 – The solute particles can be seperated from colloides by filtration
4 – Potential energy equals m . g . h
5 – Molarity is an intensive property.
6 – There are 3 significant figures in the number 20.031.
7 – Nonmetals react with each other to form ionic compounds
8 –In osmosis, the solvent passes from the concentrated to the dilute solution
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2) Choose the correct answer (16 point)
1)
For an isothermal change
the system is insulated
b) the temperature change
a + b
d) the temperature remains constant
2)
Specific heat:
a)
has the units J/g 0C
b) is an intensive property
c) a +
b
d) is an extensive property
3)
Dipole-Dipole attractions
a) are stronger than London forces
b) are 5% as strong as covalent bonds
c) a+ b
d) are stronger than hydrogen bonds.
4)
The vapor pressure of a liquid
a)
depends on the temperature
b) depends on the intermolecular forces
c)
a + b
d) depends on the volume of the vapor
5)
Hfus of benzene
a)
is less than its Hevap
b) has a negative sign
c)
is equal to its Hevap
d) none of the above
6)
Colloids
a)
can be separated by filtration
b) have very large particle size
c)
show Tyndall effect
d) a + c.
7)
Ideal solutions
a)
are 1M solutions
b) show negative deviation from Raoult’s law.
c)
Hsolution = 0
d) Hsolution > 0
8) What is the voume of 3.0 g of N2 (M. Wt = 28) in L at STP (R = 0.0821 atm.L/mol.K)
a)
2.6
b) 0.36
c)
2.4
d) 1.2
3) What is the oxidation number of the following elements (4 points)
a)
C in Na2CO3
b)
Cl in HClO3
4) Name the following compounds (6 points)
a)
CuSO4
b)
IF5
c)
Ca(Br)2
a)
c)
1
Answer the following problems and mark (X) on the following table
1
A
b
c
d
2
A
b
c
d
3
A
b
c
d
4
A
b
c
d
5
A
b
c
d
6
A
b
c
d
7
A
b
c
d
8
A
b
c
d
9
A
b
c
d
10
A
b
c
d
11
A
b
c
d
12
A
b
c
d
13
A
b
c
d
14
A
b
c
d
15
A
b
c
d
2
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1) Consider the reaction below
How many grams of Hydrogen will result from the reaction of 3.0 g of iron (At. M. =
56.0) with 30 mL of 0.40 M HCl.
Fe
a)
0.012
+
→
2HCl
b)
FeCl2
+
H2
0.3
c)
1.2
d)
1.7
2) A sample of N2 (M. wt = 28) in a flask at 25 oC exerts a pressure of 525 torr. When 0.100 g
0f O2 (M. Wt = 32) is added to this flask, the pressure rises to 760 torr. The temperature remains
constant and there is no reaction between oxygen and nitrogen. How many grams of N2 were in the
flask? (R = 0.0821 atm.L/mol.K)
a) 0.11
b) 0.12
c)
0.195
d) 0.09
=====================================================================
3) What is the mass of ethylene glycol (M. Wt. = 62.0) that is needed to cause a freezing point
depression of 6.0 oC for 500 g of water ?
a)
38.4
b)
(Kf for water = 1.86 oC/m)
225
c)
3
100
d)
134
4) A 3.0 g of NaCl (F. Wt. = 58.5) are dissolved in 15 ml of water, What is the molarity of this
solutioin
a)
3.4
b)
0.0034
c)
0.15
d)
0.23
5) What volume in mL of the above solution is needed to prepare 50 ml of 0.20 M NaCl
solution?
a)
3.6
b)
22.5
c)
15
d)
2.9
=======================================================================
6) Given the following thermo chemical equations:
a)
b)
Mg3N2 +
N2
+
3H2 →
3H2 →
3Mg +
2NH3
2NH3
∆Ho = 371 KJ
∆Ho = - 92 KJ
Calculate the value of ∆Ho for the following reaction
Mg +
a)
93
→
1/3 N2
b)
1/3 Mg3N2
- 154.3
c)
4
279
d)
463
A 1.40 g sample of an organic compound containing only carbon hydrogen and oxygen was burned
in oxygen to produce 2.062 g CO2 and 0.846 g H2O.
7) What is the number of mols of carbon in the above compound
a)
6.744
b)
0.562
c)
0.321
d)
0.047
0.512
d)
0.634
CH2O
d)
CH4O
8) What is the mass of oxygen in the above compound
a)
0.934
b)
0.744
c)
9) What is the empirical formula of the compound?
a)
CHO
b)
C2H2O
c)
=======================================================================
10) Calculate the osmotic pressure, in torr, of an aqueous solution containing 2.50 g of
sucrose (M. Wt. = 342) in 500 ml of water at 25 oC. (R = 0.0821 atm. L / mol K)
a) 272
b) 136
c)
214
d) 330
5
11) What would be the final temperature if we mix 2.0 g of steam at 100 oC
with 20.0 g of water at 0 oC?..(Sp. heat of water = 4.18 J / g
∆Hevap of water = 40.6 KJ / mol)
a)
12)
71.1
b)
24.3
c)
58.1
o
C,
d)
35.6
A solution that is prepared by mixing 5.0 g of CCl4 (M. Wt = 154) with 5.0 g of
CHCl3 (M. Wt = 119.5) have a vapor pressure that equals 435 torr at 25 oC.
What is the vapor pressure of pure CHCl3 at 25 oC if the vapor pressure of CCl4 at this temperature
is 317 torr?
a) 498
b) 577
c)
603
d) 524
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