Chemistry 1211 Practice Exam II Page 9
Chemistry 1211
Practice Exam II
Name______
This practice exam is designed to be similar to a second exam for the course. You should attempt this exam without the use of notes, books, or help and you should time yourself, although this practice test is probably longer than the real exam.
When finished, grade your exam using the exam answers, but do not look at the answers before you attempt the exam. You should then be able to tell how well prepared you are for the second exam of your course. Use this as an evaluation tool to help you decide on areas that may need more study time. Good luck, let me know if I can be of any assistance.
DATA
The first part of the exam consists of 50 multiple choice questions.
1. What is the molarity of a solution prepared by mixing 9.5 g C3H8O3 (MW = 92) with enough water to have a total volume of 31.5 ml?
a. 0.10 M b. 0.40 M c. 3.3 x 10-3 M d. 3.3 M e. 300 M
2. A pressure of 1.00 atm is the same as a pressure of:
a. 193 mm Hg b. 101 torr c. 760.0 mm Hg d. 760 in Hg e. 29.92 torr
3. What is the result of mixing solutions of sodium sulfate with lead (II) nitrate?
Data: lead (II) sulfate is a solid.
a. Na2SO4 (aq) + Pb(NO3)2 (s) b. NaNO3 (aq) + PbSO4 (g)
c. NaNO3 (aq) + PbSO4 (s) d. NaNO3 (s) + PbSO4 (aq)
e. It is not possible to tell from the information given.
4. A sample of gas (24.2 g) initially at 4.00 atm was compressed from 8.00 L to 2.00 L at constant temperature. What is the new gas pressure?
a. 4.00 atm b. 2.00 atm c. 1.00 atm d. 8.00 atm e. 16.00 atm
5. In the following reaction, determine which substance is the reducing agent.
3 H2S + 2 NO3¯ + 2 H+ ® S + 2 NO + 4 H2O
a. H2S b. NO3¯ c. H+ d. S e. NO f. H2O g. None of these
6. A balloon originally had a volume of 4.39 L at 44 °C and a pressure of 729 torr. The balloon must be cooled to what temperature (°C) to reduce its volume to 3.78 L at constant pressure?
a. 38 b. 0 c. 72.9 d. 273 e. 546
7. Which of the following is a form of potential energy?
a. heat b. light c. dynamite exploding d. compressed spring e. electricity
8. Which of the following solutions contains the largest number of moles of chloride ions?
a. 10.0 mL of 0.500 M BaCl2 b. 4.00 mL of 1.000 M NaCl
c. 7.50 mL of 0.500 M FeCl3 d. 25.00 mL of 0.400 M KCl
e. 30.00 mL of 0.100 M CaCl2
9. If 3.21 mole of a gas occupies 80.1 L at 44 °C and 793 torr, what volume (L) would 5.29 moles of the gas occupy under these conditions?
a. 18.4 b. 48.6 c. 0.174 d. 132 e. 478
10. If two objects are in contact with each other and object 1 is at a higher temperature than object 2; which of the following statements is correct?
a. heat cannot flow between the two objects
b. heat flows from object 2 to object 1
c. heat flows from object 1 to object 2
d. the temperature of object 1 should increase
e. the temperature of object 2 will remain the same
11. If 50.75 grams of a gas occupies 10.0 L at STP, 129.3 grams of the gas would occupy what volume (L) at STP?
a. 3.92 b. 50.8 c. 12.9 d. 25.5 e. 5.08
12. A sample of H2 gas (12.28 g) occupies 100.0 L at 400.0 K and 2.00 atm. What volume (L) would a sample weighing 9.49 g occupy at 353 K and 2.00 atm?
a. 109 b. 68.8 c. 54.7 d. 147 e. 77.3
13. How many moles of K+ are present in 343 mL of a 1.27 M solution of K3PO4?
a. 0.436 b. 1.31 c. 0.145 d. 3.70 e. 11.1
14. A sample of an ideal gas (3.00 L) in a closed container at 25 °C and 76.0 torr is heated to 300 °C. What is the new pressure (torr) of the gas at the new temperature?
a. 912 b. 146 c. 76.5 d. 39.5 e. 2.53 x 10-2
15. Calculate the concentration (M) of sodium ions in a solution made by diluting 50.0 mL of a 0.874 M solution of sodium sulfide to a total volume of 250.0 mL.
a. 0.175 M b. 4.37 M c. 0.525 M d. 0.350 M e. 0.874 M
16. The molarity of an aqueous solution containing 52.5 g of sucrose, C12H22O11, in 35.5 mL of solution is…
a. 5.46 b. 1.48 c. 0.104 d. 4.32 e. 1.85
17. The reaction of 50 mL of Cl2 gas with 50 mL of CH4 gas via the equation:
Cl2 (g) + CH4 (g) ® HCl (g) + CH3Cl (g)
will produce what total volume (mL) of products if pressure and temperature are kept constant?
a. 100 b. 50 c. 200 d. 150 e. cannot be determined
18. How much 0.827 M KOH is required for neutralization in a titration of 35.00 mL of 0.737 M H2SO4?
a. 35.0 mL b. 1.12 mL c. 25.8 mL d. 62.4 mL e. 39.3 mL
19. The amount of gas that occupies 60.82 L at 31 °C and 367 mm Hg is:
a. 1.18 mole b. 0.850 mole c. 894 mole d. 11.6 mole e. other
20. The value of ∆H for the reaction below is -790 kJ. The enthalpy change for the reaction of 0.95 grams of S would be…
2 S (s) + 3 O2 (g) ® 2 SO3 (g)
a. 23 kJ b. -23 kJ c. -12 kJ d. 12 kJ e. -790 kJ
21. The pressure of a sample of CH4 gas (6.022 g) in a 30.0 L vessel at 402 K is:
a. 2.42 atm b. 6.62 torr c. 0.414 atm d. 12.4 torr e. 22.4 atm
22. The value of ∆H for the reaction below is -1107 kJ. The ∆H for the reaction of 15.75 g of Ba (s) completely reacting with oxygen is…
2 Ba (s) + O2 (g) ® 2 BaO (s)
a. 20.8 kJ b. 63.5 kJ c. 114 kJ d. 70.3 kJ e. 35.1 kJ
23. At what temperature does 0.444 mole of CO gas occupy 11.8 L at 889 torr?
a. 379 °C b. 73 °C c. 14 °F d. 32 K e. 106 °C
24. The specific heat of lead is 0.13 J/g·K. How much heat (in J) is required to raise the temperature of 15 g of lead from 22 °C to 37 °C?
a. 2.0 b. -0.13 c. 5.8 x 10-4 d. 29 e. 0.13
25. A 0.325 L flask filled with gas at 0.914 atm and 19 °C will contain how much gas?
a. 1.24 x 10-2 g b. 1.24 x 10-2 mole c. 9.42 moles d. 12.4 g e. 80.7 kg
26. Given the following reactions: (1) 2 NO ® N2 + O2 ∆H = -180 kJ
(2) 2 NO + O2 ® 2 NO2 ∆H = -112 kJ
What is the ∆H for: N2 + 2 O2 ® 2 NO2
a. 68 kJ b. -68 kJ c. -292 kJ d. 292 kJ e. -146 kJ
27. A sample of gas (1.9 mole) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is added to the flask. The new pressure is 795 torr and the temperature is now 26 °C. How many moles of gas are currently in the flask?
a. 1.6 b. 2.1 c. 2.9 d. 3.5 e. 0.28
28. Given the data in the table here, calculate the ∆H for the reaction:
4 NH3 (g) + 5 O2 (g) ® 4 NO (g) + 6 H2O(l)
a. -1172 kJ b. -150 kJ c. -1540 kJ d. -1892 kJ e. other
29. The internal energy of a system can be increased by…
(1) transferring heat from the surroundings to the system
(2) transferring heat from the system to the surroundings
(3) doing work on the system
a. (1) only b. (2) only c. (3) only d. (1) and (3) e. (2) and (3)
30. The density of ammonia gas in a 4.32 L container at 837 torr and 45.0 °C is:
a. 3.86 g/L b. 0.717 g/L c. 0.432 g/L d. 0.194 g/mL e. 4.22 x 10-2 mL
31. Which of the following is a statement of Hess’s law?
a. If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the sum of the enthalpy changes for the individual steps.
b. If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the product of the enthalpy changes for the individual steps.
c. The ∆H for a process in the forward direction is equal in magnitude and opposite in sign to the ∆H for the process in the reverse direction.
d. the ∆H for a process in the forward direction is equal to the ∆H for the process in the reverse direction.
e. The ∆H of a reaction depends on the physical states of the reactants and products.
32. The molecular mass of a gas that has a density of 6.70 g/L at STP is:
a. 496 b. 150 c. 73.0 d. 3.35 e. 0.298
33. The specific heat of liquid mercury is 0.14 j/g·K. How many joules of heat are needed to raise the temperature of 5.00 g of mercury from 15.0 °C to 36.5 °C?
a. 7.7 x 102 b. 15 c. 36 d. 0.0013 e. 1.7
34. What is the volume of hydrogen gas (L) at 38.0 °C and 763 torr that can be produced by the reaction of 4.33 g of zinc with excess sulfuric acid?
a. 1.69 b. 2.71 x 10-4 c. 3.69 x 104 d. 2.84 e. 0.592
35. Automobile air bags use the decomposition of sodium azide as their source of gas for rapid inflation:
2 NaN3 (s) ® 2 Na (s) + 3 N2 (g)
What mass (g) of NaN3 is required to provide 40.0 L of N2 at 25.0 °C and 763 torr?
a. 1.64 b. 1.09 c. 160 d. 71.1 e. 107
36. What volume (L) of NH3 gas at STP is produced by the complete reaction of 7.5 g of H2O according to the equation:
Mg3N2 (s) + 6 H2O (l) ® 3 Mg(OH)2 (aq) + 2 NH3 (g)
a. 3.1 b. 9.3 c. 19 d. 28 e. 0.32
37. A vessel contained N2, Ar, He, and Ne. The total pressure in the vessel was 987 torr. The partial pressures of nitrogen, argon and helium were 44.0, 486, and 218 torr, respectively. What is the partial pressure of the neon in torr?
a. 42.4 b. 521 c. 19.4 d. 239 e. 760
38. A sample of N2 gas (0.0020 mole) effused through a pinhole in 5.5 sec. How long will it take the same amount of CH4 to effuse under the same conditions?
a. 7.3 sec b. 5.5 sec c. 3.1 sec d. 4.2 sec e. 9.6 sec f. > 1 minute
39. A sample of He gas (0.0020 mole) effused through a pinhole in 53 sec. The same amount of an unknown gas, under the same conditions, effused through the pinhole in 248 sec. What is the molecular mass (g/mole) of the unknown gas?
a. 0.19 b. 5.5 c. 88 d. 19 e. 350
40. Which of the following statements about gases is false?
a. gases are highly compressible
b. distances between molecules of a gas are very large compared to bond distances within the gaseous molecule
c. non-reacting gas mixtures are homogeneous
d. gases expand spontaneously to fill the container they are placed in
e. all gases are colorless and odorless at room temperature
41. Gaseous mixtures:
a. can only contain molecules b. are all heterogeneous
c. can only contain isolated atoms d. are all homogeneous
e. must contain both isolated atoms and molecules
42. Of the following, which is impossible for ideal gases?
a. V1T1 = V2T2 b. V1T1 = V2T2 c. V1V2 = T1T2 d. V2 = T2T1 V1 e. . V1V2 = T1T2 = 0
43. Which statement below about ideal behavior of gases is false?
a. at low densities all gases have similar properties
b. volume of 2.00 moles of oxygen gas, O2, is assumed to be the same as that of 2.00 moles of carbon dioxide gas, CO2, as long as the temperature and pressure conditions are the same
c. ideal behavior of gases assumes that there are no interactions between gas particles
d. all particles in the ideal gas behave independently of each other
e. low pressure and high temperature typically cause deviations from the ideal gas behavior
44. The volume of a sample of gas (2.49 g) was 752 mL at 1.98 atm and 62 °C. the gas is:
a. SO2 b. SO3 c. NH3 d. NO2 e. Ne f. more information is needed
45. The kinetic-molecular theory predicts that pressure rises as the temperature of a gas increases because:
a. the average kinetic energy of the gas molecules decreases
b. the gas molecules collide more frequently with the wall
c. the gas molecules collide less frequently with the wall
d. the gas molecules collide more energetically with the wall
e. both b. and d.
46. The van der Waals equation for real gases recognizes that:
a. gas particles have non-zero volumes and interact with each other
b. molar volumes of gases of different types are different
c. the non-zero volumes of gas particles effectively decrease the amount of “empty space” between them
d. the molecular attractions between particles of gas decreases the pressure exerted by the gas
e. all of the above statement are true
47. At 333 K, which of the pairs of gases below would have the most nearly identical rates of effusion?
a. N2O and NO2 b. CO and N2 c. N2 and O2 d. CO and CO2 e. NO2 and N2O4
48. In which species does sulfur have the highest oxidation number?
a. S8 (elemental form of sulfur) b. H2S c. SO2 d. H2SO3 e. K2SO4
49. Which of the following is the correct expression for molarity?
a. mole solute / liter of solvent b. mole solute / mL solvent
c. mole solute / liter of solution d. mole solute / kg solvent
e. mole solute / kg of solution f. grams solute / liter solution
50. The ΔH for the solution process when solid sodium hydroxide dissolves in water is 44.4 kJ/mole. When a 13.9 g sample of NaOH dissolves in 250.0 g of water in a coffee-cup calorimeter, the temperature increases from 23.0 °C to:
(Assume the solution has the same specific heat as water, 4.18 J/g·K)
a. 35.2 °C b. 24.0 °C c. 37.8 °C d. 37.0 °C e. 40.2 °C
The remainder are “show your work” type of problems.
51. Write the net ionic equations for each of the following:
H2SO4 (aq) + NaOH (aq) ®
NiCO3 (s) + HI (aq) ® NiI2 (aq) + CO2 (g) + ??
52. Balance each of the following REDOX reactions using the half-reaction method. Show your work clearly.
A. Ag+ + AsH3 ® As4O2 + Ag (Acidic Solution)
B. Al + H2O ® Al(OH)4¯ + H2 (Basic Solution)
C. Na2Cr2O7 + HCl ® NaCl + CrCl3 + Cl2 (Acidic Solution)
53. An aqueous solution is made from 0.798 g of potassium permanganate. If the volume of the solution is 50.0 mL, what is the molarity of the solution?
50. A mixture contained calcium carbonate and magnesium carbonate. A sample of this mixture weighing 7.85 g was reacted with excess hydrochloric acid, HCl. The reactions both produce carbon dioxide and water. If the sample reacted completely and produced 1.94 L of carbon dioxide at 25 °C and 785 mm Hg, what were the percentages of each salt in the mixture?
Answers: Don’t look until you have attempted the problems. (If you find errors, let me know)