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Unformatted text preview: UNIVERSITY OF WATERLOO
DEPARTMENT OF CHEMICAL ENGINEERING ChE 102 MIDTERM EXAMINATION Saturday, October 27th, 2007
10:00 a.m.  Noon Instructors: .
J Scares (coordinator), J Grove, R Legge, N McManus, C Madhuranthakam, H Park, M Robinson, M Tam Aids Allowed: Electronic calculator and one single 8V2" x 11" piece of paper — written on both
sides. Instructions:
0 The sense card must be ﬁlled outwith a pencil — HB or F only. BEFORE YOU BEGIN: .
0 Print your NAME and student ID. Number in the spaces provided. 0 Code your student ID. Number into the spaces provided.
0 Ovals on the card must be completely ﬁlled in with a black mark — see examples on card. 0 Cards must not be folded, spindled or mutilated.
0 Hand in only the computer card. It is a good idea to record your answers on this exam paper and keep it for reference. 0 Each multiplechoice question is supposed to have only one correct answer. In the case of
numerical answers, choose the one closest to the correct answer. 0 All questions in the exam have the same weight. 0 Marks are not deducted for incorrect answers. Data: You are provided with a formula sheet, tables of conversion factors and constants and a periodic
table. You may assume that the molar mass of dry air is 29 gmol‘1 and that the composition is 21 mol—%
0; and 79 mol% N2, unless stated otherwise in the question. ChElOZ MidTerm Examination . _ 27‘h October. 2007 This examination contains 12 questions. Answer all questions. 1. [\3 Stainless steel, type 304 has a thermal conductivity, k, of 0.067 cals‘lcm'lﬁC—l.
What is this value expressed in Btuh‘lfflﬂlr 1? A. 3.87 B. 4.94 C. 9.1 .62 E. 29.6 Ammonia reacts with Oz to form either NO or N02 according to the unbalanced
equations shown below. NH3+Oz—>NO+H20
NH3+ 02—9 N02+H20 In an experiment, 2.00 mol NH3 and 10 mol of 02 are reacted in a closed ﬂask. ,
After the reaction, all the NH3 is consumed and 6.75 mol of Oz remain. Calculate
the number of moles of NO in the ﬂask after reaction. A. 2 @1 C. 0.5 D. 0.2 E. 0.1 How many grams of calcium phosphate are formed by the neutralization of 20 mL
of 0.15 M phosphoric acid with 10 mL of 0.3 M calcium hydroxide in the unbalanced equation below?
C3(OH)2(aq) + H3PO4(aq) —> C33(PO4)2(s) + H200) A. 0.015 B. 0.215 @0310
D. 0.360 E. 0.520 A 6.24 g sample of Rb2803 reacts with 1.38 L of gaseous HBr, measured at 75 °C
and 0.953 atm, according to the unbalanced reaction below. 7.32 g of RbBr is
produced. What is the percentage yield of RbBr? Rb2803 + HBr —> RbBr + H2803 .6% B. 93% C. 89% D. 84% i E. 48% Calcium carbonate decomposes when heated to give C02 gas and calcium oxide,
according to the following reaction: C3CO3(5) '9 C02(g) + CaO(s) A sample of impure calcium carbonate weighing 25.0 g was heated until no more
gas could be driven off. CaCO3 is the only substance in the sample to lose weight
when heated. 4.85 L of C02 was collected at 0.98 atm and 22 °C. What was the
percentage of CaCO3 on a mass basis in the original sample? . A. 19.6% B. 21.4% C. 34.4% (3. 78.6% E. 80.4% Page 2 of7 ChE102 Mid—Term Examination 27‘h October. 2007 6. A 1.50 L container contains a mixture of oxygen and hydrogen gases. The partial
pressure of oxygen is 0.200 atm and hydrogen is 0.800 atm at 40 °C. Assuming
that the reaction goes to completion, how many grams of water will be produced? H2 + 1/2 Oz ‘9 H30
A. 1.68 @0421 C. 0.234 D. 00934 E. 0.0467 7. ‘ Read the following statements and determine which are true and which are false:
i. Real gases follow the ideal gas equation only at sufﬁciently low densities. ii. The van der Waals equation does not take the volume of the gas molecules
into account. T iii. In the van der Waals equation, the values of a and b are determined from
experimental data”T iv. Attractive forces dominate when Z, the compressibility factor, is less than one. How many of the above statements are true? A.0 13.1 @2 D.3' E4 8. Two containers of argon (Ar) gas are illustrated below. Both containers contain
the same number of moles of argon and are at the same temperature. Constant T
Constant n Read the following statements and determine which are true and which are false:
i. The rms speed of the argon is the same in both containers /V
ii. Every argon atom has the same kinetic energy in both containers F iii. The frequency with which argon atoms collide with the walls is the same in
both containers F iv. The average force with which the argon atoms strike the wall is the same in
both containers ’1’ How many of the above statements are true? A. 0 B. 1 @2 D. 3 E. 4 Page 3 of7 ChE102 MidTerm Examination 27‘h October, 2007 9. A 7.5 g copper coin is at a temperature of 18.8 0C. The coin is placed in 10.0 g of
water at a temperature of 54.0 0C. What is the ﬁnal temperature, in 0C, of the coin and water, assuming no heat is lost to the surroundings?
Data: cc. = 0.385 J‘g'1'0C71; cm... = 4.18 igloo”.
A. 23.2 B. 35.4 C. 44.1 @517 13.60 10. A glass containing 200 g of H20 at 20 °C is placed in a refrigerator. The water
loses 11.7 k] as it cools to a constant temperature. What is its new temperature in OC?
Data: The speciﬁc heat ofwater is 4.18 Jg‘lOC. A. 0.013 B. 4 @ D. 14 E. 34 11. A bomb calorimeter contains 2.00 L of liquid. A combustion reaction takes place
in the bomb and releases 16.73 k] of heat. The experiment is ﬁrst conducted using
water as the liquid, and the temperature rises by 1.62 K. When the experiment is
repeated using liquid hexane (C6H14) in place of water, the temperature of the
system rises by 3.10 K. ' D
Estimate the speciﬁc heat capacity of hexane in—leJanaeFlQglr T/a C Data: For water: ,0: 1.00 gmL‘lg c = 4.18 Jg_1°C'1.
For hexane: p = 0.659 gmL'l. A. 2.18 B. 2.60 @09 D. 5.27 E. 8.00 12. An automobile piston of diameter 5.00 cm is displaced 8.00 cm when the cylinder 7
ﬁres. If the gas expands against an external pressure of 3.50 atm, how much work,
in J, is done on the gas for each expansion stroke of the piston? Data: The volume of a cylinder V= nrzh, where r is the radius and h the height.
A. 55.57 B. 5.7 CO D. —5.57 CED55.7 There are no more questions. Check that you have coded one answer (in pencil) for
each of questions 1 to 12 on your answer card. Page 4 of 7 ...
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 Fall '08
 SIMON
 Chemistry

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