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CHEM 150
Exam 2
_______________________________
Name
Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.
____
1. Formic acid, HCOOH, is what causes the sting of bee stings. What is the formula weight of
formic acid?
a. 29 amu
b. 46 amu
c. 50 amu
d. 58 amu
____
2. What is the weight of 300. moles of KCl?
a. 22.4 amu
b. 22.4 g
c. 74.5 amu
d. 74.5 g
____
3. The balanced equation 2H2 + O2 → 2H2O means which of the following?
a. two grams of hydrogen react with one gram of oxygen to form two grams of water
b. two moles of hydrogen react with one mole of oxygen to form two mole of water
c. the equation represents both (a) and (b)
d. the equation represents neither (a) nor (b)
____
4. What do we call the chemicals which appear to the right of the arrow in a balanced chemical
equation?
a. products
b. reactants
c. reagents
d. none of the above
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5. Which of the following is the correctly balanced equation for the complete combustion of
methane, CH4?
a. CH4(g) + O2(g) → H2O(g) + CO(g)
b. CH4(g) + O2(g) → H2O(g) + CO2(g)
c. 2CH4(g) + 5O2(g) → 4H2O(g) + 2CO(g)
d. CH4(g) + 2O2(g) → 2H2O(g) + CO2(g)
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6. A classic method for generating molecular oxygen is the decomposition of potassium chlorate,
KClO3. The other product of this reaction is potassium chloride. Which of the following is the
correctly balanced chemical equation for this reaction?
a. KClO3(s) → KCl(s) + 3O(g)
b. 2KClO3(s) → 2KCl(s) + 3O2(g)
c. KClO3(s) → KCl(s) + O3(g)
d. 2KClO3(s) → K2Cl2(s) + 3O2(g)
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7. For the reaction 2H2 + O2 → 2H2O which of the following can be answered only using the
coefficients of the balanced equation?
a. What weight of water is produced when 2.5 grams of hydrogen react completely?
b. What weight of water is produced when 2.5 moles of hydrogen react completely?
c. How many moles of water are produced from 4.0 grams of hydrogen and 32.0 grams of
oxygen?
d. How many moles of water are produced when 2.5 moles of hydrogen react completely?
____
8. The balanced equation for the complete combustion of propane is
C3H8(g) + 5O2(g) → 4H2O(g) + 3CO2(g)
If 1 mole of propane and 10 moles of oxygen are placed in container, what will be left in the container after
the reaction is complete?
a. no propane, 5 moles of oxygen, 4 moles of water vapor, 3 moles of CO2
b. no propane, no oxygen, 4 moles of water vapor, 3 moles of CO2
c. no propane, no oxygen, 8 moles of water vapor, 6 moles of CO2
d. none of the above combinations is correct
____
9. When ammonia gas comes in contact with hydrogen chloride gas the reaction is
NH3(g) + HCl(g) → NH4Cl(s)
What weight of ammonium chloride, NH4Cl(s), is produced by the reaction of 34.0 grams of NH3(g) with
75.0 grams of HCl(g)?
a. 34.0 g
b. 75.0 g
c. 107 g
d. 109 g
____ 10. Aspirin can be made by the following reaction:
C7H6O3(s) +
Salicylic
acid
2C4H6O3(l)
acetic
anhydride
→
C9H8O4(s)
aspirin
+
C2H4O2(l)
acetic
acid
If this reaction is carried out with a 95.0% yield, how much salicylic acid is needed to produce
90.0 grams of aspirin?
a. 65.6 g
b. 69.0 g
c. 72.6 g
d. 138 g
____ 11. Which of the following is the balanced molecular equation for the reaction of silver nitrate,
AgNO3, with barium chloride, BaCl2?
a. AgNO3(aq) + BaCl2(aq) → AgCl(s) + BaNO3(aq)
b. 2AgNO3(aq) + BaCl2(aq) → 2AgCl(s) + BaNO3(aq)
c. AgNO3(aq) + BaCl2(aq) → AgCl2(s) + BaNO3(aq)
d. 2AgNO3(aq) + BaCl2(aq) → 2AgCl(s) + Ba(NO3)2(aq)
____ 12. Oxidation can be defined as which of the following?
a. loss of oxygen
b. loss of electrons
c. gain of hydrogen
d. all of these correctly define oxidation
____ 13. In a redox reaction which of the following is true for the oxidizing agent?
a. it accepts electrons
b. it is reduced
c. both (a) and (b) are true
d. both (a) and (b) are false
____ 14. Which of the following is true about the combustion of a hydrocarbon?
a. combustion is not a redox reaction
b. oxygen is the oxidizing agent
c. the hydrocarbon is the oxidizing agent
d. all of these are true
____ 15. Which of the following is true of a reaction in which heat is consumed?
a. the reaction is endothermic
b. the reaction is exothermic
c. depending on the reaction the reaction may be either endothermic or exothermic
d. there are more reactants than products
____ 16. Which of the following is a unit used for air pressure?
a. atmospheres
b. millimeters of Hg
c. torr
d. all of these
____ 17. Which of the following exerts the greatest pressure?
a. a 20 gram object on a surface of 0.50 cm2
b. a 40 gram object on a surface of 2.0 cm2
c. a 60 gram object on a surface of 3.0 cm2
d. an 80 gram object on a surface of 3.5 cm2
____ 18. At constant temperature the pressure on a 6.0 liter sample of gas is increased from 1.0 atm to 2.0
atm. What is the new volume of the gas sample?
a. 0.33 liters
b. 0.67 liters
c. 1.5 liters
d. 3.0 liters
____ 19. Suppose a balloon is filled so that its volume is 2.00 L when the pressure is 1.10 atm and the
temperature is 300 K. What volume will it occupy if it rises to an elevation where the pressure is
418 torr and the temperature is 200 K?
a. 3.30 liters
b. 2.67 liters
c. 0.375 liters
d. 0.303 liters
____ 20. If a 7.00 gram sample of molecular nitrogen at 10oC occupies 2.50 L, what is the pressure of the
sample?
a. 1.28 atm
b. 2.32 atm
c. 2.56 atm
d. 4.65 atm
____ 21. A closed flask contains a 0.25 moles of O2 which exerts a pressure of 0.50 atm. If 0.75 moles of
CO2 is added to the container what is the pressure of oxygen?
a. 0.50 atm
b. 1.0 atm
c. 1.5 atm
d. 2.0 atm
____ 22. Which of the following is not an example of an intermolecular attraction?
a. covalent bonding
b. dipole-dipole interactions
c. London dispersion forces
d. hydrogen bonding
____ 23. Which of the following molecules can have only London dispersion forces?
a. CH4
b. CO2
c. both (a) and (b)
d. neither (a) nor (b)
____ 24. Which of the following molecules cannot engage in hydrogen bonding?
a. CH4
b. NH3
c. H2O
d. all of them
____ 25. When comparing a liquid with a gas at the same temperature which of the following is true?
a. the molecules in the liquid are much closer together than those in the gas
b. the molecules in the liquid have greater kinetic energy than those in the gas
c. both (a) and (b) are true
d. both (a) and (b) are false
____ 26. Which of the following affects the vapor pressure of a liquid?
a. the mass of the sample
b. the shape the sample
c. the temperature of the sample
d. the volume of the sample
____ 27. Chloroform has a normal boiling point of 61.7oC. Which of the following is true?
a. at any temperature the vapor pressure of chloroform is greater than that of water
b. chloroform is less volatile than water
c. both (a) and (b) are true
d. both (a) and (b) are false
____ 28. Which regions of a heating curve correspond to regions where only a single phase of a material is
present?
a. horizontal regions
b. regions with negative slope
c. regions with positive slope
d. it depends on the material
____ 29. Which of the following phase changes does not involve a solid?
a. evaporation
b. melting
c. sublimation
d. none, they all involve a solid
Phase diagram of water. The temperature and pressure scales are greatly reduced (and are non-linear).
____ 30. Refer to the Figure above. Consider a sample of water initially at a temperature of 0oC and a
pressure of 660 torr. If the pressure is increased to 800 torr while the temperature is held constant,
what phase transition will occur?
a. solid to liquid
b. solid to vapor
c. liquid to vapor
d. no phase change will occur
31. In the space provided, draw the Lewis dot structure of (remember to include lone pair electrons, if present, into
your drawing):
a. CH3NH2 (3 points)
b. GeF4 (3 points)
32. In photosynthesis, green plants convert CO2 and H2O to glucose, C6H12O6. How many grams of CO2 are
required to produce 5.1 g of glucose? (6 points)
CO2(g) + H2O → C6H12O6(aq) + O2(g)
(Note: unbalanced)
33. What volume is occupied by 3.9 g of propane gas, C3H8, at 28 °C and 2.13 atm pressure? (R = 0.0821
L•atm/mol•K, 3 points)
34. What will be the final temperature (in °C) when we add 1500 cal of heat to 8 g of ice at 0 °C? (Ice: Heat of
Fusion = 80 cal/g; Water: Specific Heat = 1.00 cal/g•°C) (5 points)