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Unformatted text preview: CHEM 3530  Exam 1  February 11, 2010 Constants and Conversion Factors
NA = 6.02x1o23 mor1
R = 8.31 J/moIK = 8.31 kPaL/molK 1 bar = 100 kPa
1 kPa = 7.50 torr
1 J = 1 kPaL Molar Masses C5H1206  180. H20  18. H2  2.
CH4  15. CgHs  30. CgHg  44.
He  4. $02  64.1 002  44. C3H13  Csz  CHEM 3530  Exam 1 — February 11, 2010 Name 5; Note: I know there are only 94 points on this test (due to its being cut down after the missed
classes). l will add 6 points to your score to arrive at a ﬁnal percent (before putting on any
curve). (57) PART I. MULTIPLE CHOICE (Circle the ONE correct answer) 1. 45 grams of glucose, CsH1205 contains how many atoms of Owgen? (B) 1.5x1o23 (C) 6.8x1022 (D) 2.5x1022 2. A sample of a gas has a volume of 1.5 L at a pressure of 600 torr and
temperature of 50 °C. The number of molecules in the ample is: (A) 1.7x1o23 (B) 4.3x1o22 (D) Cannot be determined without the gas’s Molar Mass 3. A 25. L container has 48. grams of CH4(g) at 200 °C. What is the pressure of
this gas, in bar? (A) 2.0 bar (C) 200 bar (D) 470 bar 4. At 100 °C and 0.65 atm, a gas occupies a volume of 0.60 L. How many Liters
will the gas occupy at 3.00 °C and 0.25 am? (A) 0.35 L (B) 1.0 L (D) 4.7 t. 5. A sample of a gas is initially at 300 torr and 20 °C. If the pressure on the gas is increased to 500 torr at constant volume, what is the ﬁnal temperature of the
gas (in °C)? (A) 33°C (B) 97°C (0) 488°C 6. A container has a gaseous mixture of 6. grams of H2(g) and 32 grams of CH4(g).
The partial pressure of H2(g) is 150 kPa. What is the partial pressure of CH4(g)
in the mixture? A 100 kPa (B) 250 kPa (C) 650 kPa (D) Cannot be determined without the container’s temperature and volume 7. The RMS average speed of CZH6(g) molecules at 800 °C is 940 mls. What is the
RMS average speed of CH4(g) molecules at 800 °C ? (A) 1760 m/s (B) 1290 m/s (C) 690 m/s (D) 500 m/s 10. 11. 12. 13 14. 15 The RMS average speed of C2H6(g) molecules at 800 °C is 940 mls. What is the
RMS average speed of C2H6(g) molecules at 200 °C ? (A) 410 m/s B) 620 m/s (C) 940 m/s Consider the three gases (all at 1 bar pressure): C3H8 at 60 °C. He at 60 °C,
CH4 at 30 °C. Of these three gases, has the lowest density and
has the lowest molar kinetic energy. (A) CH4 , He (B) He , C3H5 (D) 1420 mls (C) He , He The rate of effusion of CzHe(g) through a pinhole is 18.0 molfhr. What is the rate
of effusion of 802(9) through a pinhole under the same conditions? (A) 8.4 mollhr B 12.3 mollh (C) 26.3 mollhr (D) 38.5 mollhr A sample of 002(9) effuses through a pinhole in 120 s. The same amount of an
unknown gas effuses through the pinhole in 160 s. The Molar Mass of the unknown gas is
) 78 glmol (D) 25 glmol (A) 51 glmol The compressibility factor, Z, of a gas is deﬁned as Z = PVmIRT. One mole of a
real gas at a temperature of 400 K and pressure of 100 bar has a volume of
450 mL. Therefore, and forces predominate in the gas. Z<1,repulsive (B) Z<1,attractive (D) Z>1,attractive (B) 59 glmol . The constant pressure molar heat capacity of Ar(g) is 20.8 JlmolK. What is the heat involved, in kJ, when 2.5 moles of Ar(g) is cooled from 200 0'C‘ to 50 “C at
constant volume?. (A) 1o.9 kJ The constant volume Molar heat capacity of water vapor is 25.3 JImol—K. When
7.0 M of heat is removed at constant volume from 90 grams of water vapor
initially at 180 °C, the ﬁnal temperature is (B) 235 °C (C) 7.8 kJ (D) +1o.9 kJ (C) 147 °c (D) 55 °c . For a process in which the internal energy change of a gas is 0 (zero), which of the following processes isfare possible? V (i) the gas is expanded and heated
X (ii) the gas is expanded and cooled
(,(iii) the gas is compressed and cooled 16 (A) ieﬁly (B) ii ealy (C) lead ii (A) w<0,AU>0 (C) w>O,AU>0 (D) w<0,AU=O . When a gas is expanded reversibly and adiabatlcally, 17. What are w and q when 3. moles of a gas is compressed isothermally and
reversibly from 30 L to 2 L at 50 °C? (A) w=21.8deq=0 (B) w=+21.8 kJandq=O
C) w = +21.8 kJ and q = 21.8 kJ (D) w = 21.8 kJ and q = +21.8 kJ 18. When a gas is cooled at constant pressure, (A) q>0 and w<0 (B) q>0 and w>0
(C) q<0 and w<Q D q<,.0 and W? 19. Solid tungsten, will react with gaseous carbon monoxide to form solid tungsten hexacarbonyl, according to the reaction: W(s) + 6 CO(g) —> W(CO)5(s). What is
the work involved when one mole of W(s) reacts with CO(g) to form one mole
W(CO)5(s) at 150 °C and 1 bar pressure? (B) +3.5 kg ((3,) 21.1 k; (D) 3.5 k4 PART II. PROBLEMS (Show work for partial credit) (7) 1. A sample of an unknown gas has a density of 8.0 git. at a temperature of 40 °C and
pressure of 1.8 bar. Calculate the Molar Mass of the gas, in glmol. (15) 2. The constant pressure molar heat capacity of acetylene, CzH2(g), is 43.9 J/molK.
A sample of 78 g of CZH2(g), is initially at a volume of 20 L and pressure of 4.0 bar. Calculate q, w, AU and AH when the gas is heated reversibly at constant volume
until the pressure has increased to 7.0 bar. 6:45“ WW era %m5?3’9%ﬁ / rug
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a 3:. g?“ = I'D/> /< :Na‘sxwwb’ﬁ’mr shaggy“; do (15) 3. The constant volume molar heat capacity of 002(9) is 28..5 J/molK. A sample
of 88 g of 002(9) is initially at a pressure of 2.8 bar and volume of 25. L. The gas is
expanded adiabatically arid reversibly until the pressure has decreased to 1.5 bar
volume has inereased to 40 L. Calculate 6;, w, U and AH for this process. ...
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