The Islamic University of Gaza

/ /

Chemistry Department

Engineering Chemistry
Date : 30/4/2012 / Exam II
Time: 60 min
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الرقم الجامعي ...... المدرس ......
اسم الطالب(ة) ......

Choose the correct answer (one Mark each)

1)  If two different gases are at the same temperature. Which of the following must also be equal?

a)  Their pressures / b)  Their
Volumes / c)  Their number of moles / d)  Their average kinetic energies

2)  Graham¢s law states that: Effusion rate of a gas is ………. to its square root of molar mass.

a)  Directly proportional / b)  Inversely proportional / c)  Exactly equal / d)  Not related

3) Which of the following shows ion dipole interaction between the particles?

a) NaCl/H2O / b) CaCl2/CH4 / c) Br2/CCl4 / d) H2O/CH3OH

4) Which of the following substances has the highest boiling point?

a) CH3Cl / b) CH3OH / c) CH3I / d) CH3Br

5) Which of the following substances would you expect to have the highest dispersion forces?

a) CF4 / b) CCl4 / c) CH4 / d) CBr4

6) Two sugar solutions A, and B of concentrations 0.1M and 0.5 M respectively, separated by a semipermeable membrane (غشاء شبه منفذ) .Choose the correct answer:

(a) Sugar molecules move from solution A to solution B.

(b) Water molecules move from solution A to solution B.

(c) Sugar molecules move from solution B to solution A.

(d) Water molecules move from solution B to solution A.

7) One of the following properties is not colligative:

a) Boiling point elevation c) raising a liquid in a capillary tube

b) Freezing point depression. d) Osmosis of a salt solution.

8) What is dispersion phase/ dispersions medium for smoke as a colloidal dispersion.

a) gas/solid / b) liquid/gas / c) solid/liquid / d) solid/gas


Choose the correct answer (Showing your work) (Two marks each)

1) A gas has a density of 0.08987 g/L at STP conditions. What is its molar mass ?

(R = 0.0821 L atm mol-1 K-1)

a)  2.01 g/mol / b)  2.20 g/mol / c)  2.5 g/mol / d)  3.05 g/mol

2) Given the reaction: 2Ag2O (s) ® 4Ag(s) + O2 (g) in which 1.5 g of Ag2O (MW= 332 g/mol) was heated.Calculate the volume of oxygen gas collected over water at 26° C, and barometric pressure of 751 mmHg. Given that vapor pressure of water at this temperature is 25 torr. (R = 0.0821 L atm mol-1 K-1)

a)  29.03 mL / b)  58.02 mL / c)  174 mL / d)  120 mL

3) What is the final concentration of HCl if 2.0 L of 2.2 M HCl and 1.5 L of 3.4 M HCl are mixed and diluted to 5.0 L?

a)  1.6 M / b)  1.12 M / c)  1.9 M / d)  4.32 M

4)  Calculate the enthalpy change (Q) upon converting 36 g of ice at -20 ºC to steam at 120 ºC under a constant pressure of 1 atm. Given : the specific heats of ice, liquid water, and steam are 2.03 J/g K , 4.18 J/g K and 1.84 J/g K, respectively. ΔHvap (H2O) = 40.7 kJ/mol, ΔHfus (H2O) = 6.0kJ/mol

a)  109.773 kJ / b)  96.186 kJ / c)  99.324 kJ / d)  111.23 kJ

5) An amount of 0.2 g of a high molar mass compound (non electrolyte) is dissolved in water forming 12.5 ml solution at 25 °C, and making osmotic pressure of 0.0011 atm. Calculate the molar mass of the compound. (R = 0.0821 L atm mol-1 K-1)

a) 3.56 × 105 g/mol / b) 2.98 × 105 g/mol / c) 1.56 × 107 g/mol / d) 2.98 × 103 g/mol

6) An aqueous solution is 34.0 % by mass of H3PO4 (MW = 98 g/mol) has a density of 1.209 g/mL. What is the molarity of this solution?

a) 3.47 M / b) 6.73 M / c) 4.19 M / d) 8.14 M

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