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Chem 121.09 Winter 2012 Exam III
Name ___________________________________________________
Multiple Choice Questions. Give the one best answer for each question.
1 pt each
_C___1. Which of the following reactions is both correct and balanced?
A) N2 + H3 = 2NH3
B) 2H2O + CO = CO2 + 2H2
C) Zn + 2HCl = H2 + ZnCl2
D) CO + O2 = CO2
_D___2. Which species would be considered a spectator ion based on the following equation?
Ba2+ + 2NO3- + 2Na+ + SO42+ = BaSO4(s) + 2NO3- + 2Na+
A) Ba2+
B) SO42+
C) BaSO4
D) 2NO3__C__3. How many grams of N2 are required to completely react with 3.03 grams of H2 for the
following balanced chemical equation?
N2 + 3H2 = 2NH3
A) 1.00
B) 6.00
C) 14.0
D) 28.0
3.03 g H2 X (1 mol H2/2.02g H2) X (1 mol N2/3 mol H2) X (28.0 g N2/1 mol N2)
_A___4.
A)
B)
C)
D)
Which is not a meaning of oxidation?
to gain electrons
to lose hydrogen
to combine with oxygen
to lose electrons
_A___5. 2500 liters of oxygen gas is produced at 1.00 atm of pressure. It is to be compressed and
stored in a 20.0 liter cylinder. If temperature is constant, calculate the pressure of the
oxygen in the cylinder.
A) 125 atm B) 4.0 atm C) 80.0 atm
D) 8.00 atm
__D__6. A gas sample has a volume of 500 mL at 20oC. At what Celsius temperature would the
gas have a volume half as large? [don’t forget to change to K and back]
A) 10oC
B) 147oC
C) -147oC
D) -127oC
_B___7. What pressure will 3.20 mol of N2 gas exert if confined in a 15.0 L container at 100oC?
R = 0.0821 Latm/molK
A) 1.75 atm
B) 6.53 atm C) 3.27 atm D) 13.0 atm
_C___8. Which of the following gases is least likely to behave ideally?
A) He
B) N2
C) HCl (the least non-polar)
D)
H2
_D OR A___9. Which of the following gases would diffuse slower than O2?
A) HCl
B) H2
C) He
D) Cl2 both A and D are larger
than oxygen.
_C___10. In which of the following processes does the kinetic energy of the water increase?
A) water freezes
B) steam condenses to liquid
C) water evaporates
D) more than one response is correct
_D___11. Which of the following is an exothermic process?
A) Sublimation [(s) to (g)]
B) melting
C) evaporation
D) condensation
_C___12. The vapor pressure of a liquid
A) decreases with increasing temperature
B) is independent of temperature
C) is equal to one atmosphere at the normal boiling point
D) cannot be measured
_D___13. Which of the following is not a standard condition (STP) for gas measurements?
A) 0OC
B) 1.00 atm
C) 273 K
D) 1.00 torr
_B___14. In a chemical reaction, you were able to produce 1.345 g of product although it was
theoretically possible to make 1.433 g. What was the percent yield for this synthesis? Use
the correct number of significant figures.
A) 93.859 %
B) 93.86 %
C) 94 %
D) 0.9386 %
_A___15. A salt sample is placed into water and stirred until no more will dissolve. The resulting
solution is
A) saturated
B) supersaturated C) unsaturated D) can't tell from the data given
_B___16. Which of the solutes below can most likely dissolve better if an aqueous solution is
heated?
A) oxygen B) sodium bicarbonate C) argon D) more than one correct response is
given [A and C are gases]
__C__17. Iodine, I2, is very slightly soluble in water, a polar solvent, but quite soluble in toluene,
a nonpolar solvent. What can be inferred about the nature of the I2 molecule?
A) It is ionic. B) It is polar. C) It is nonpolar. D) Nothing can be inferreD)
__A__18. When solid NaOH is dissolved in water, the solution becomes hot. The solution process
is
A) exothermic B) endothermic C) neither exo nor endothermic D) can't be classified
_A___19. A solution is made by dissolving 5.84 grams of NaCl in enough distilled water to give a
final volume of 1.00 L. What is the molarity of the solution?
A) 0.100
B) 1.00
C) 0.0250
D) 0.400
__D__20. How many moles of Na2CO3 would be needed to react with 750 mL of 0.250 M H2SO4
solution?
Na2CO3 + H2SO4 = Na2SO4 + CO2 + H2O
A) 3.00 X 103
B) 0.333
C) 1.33
D) 0.188
__D__21. A solution is made by combining 4.00 g of sugar and 100 mL of water (density = 1.00
g/mL). What is the concentration in % w/w?
A) 26.0
B) 4.00
C) 0.0400
D) 3.85
_A___22. A solution is made by dissolving 15.0 mL of oil in enough gasoline to give 50.0 mL of
solution. What is the % (v/v) of oil in the solution?
A) 30.0
B) 23.1
C) 42.9
D) 3.33
__D__23. How many mL of 6.00 M HCl are needed to prepare 1500 mL of 0.200 M HCl solution?
A) 1.80 X 104 B) 125 C) 2.00 X 10-3 D) 50.0
_A__24. The boiling point of a solution of sugar water is
A) higher than that of pure solvent B) the same as that of pure solvent
C) lower than that of pure solvent D) impossible to determine
_D___25. Two solutions with concentrations of 2% sugar and 4% sugar, respectively, are
separated by a semipermeable membrane. During osmosis, there is a net flow of
A) sugar molecules from the concentrated to the dilute solution
B) sugar molecules from the dilute to the concentrated solution
C) water molecules from the concentrated to the dilute solution
D) water molecules from the dilute to the concentrated solution
_C___26. Compared to pure water, a salt water solution will have a
A) lower vapor pressure, freezing point and boiling point
B) higher vapor pressure, freezing point and boiling point
C) lower vapor pressure and freezing point and a higher boiling point
D) higher freezing point and a lower vapor pressure and boiling point
_A___35. Which of the following pass through both osmotic and dialysis membranes?
A) water molecules
B) large molecules
C) small molecules that are larger than water molecules
D) more than one response is correct
__C__36. Which of the following is not considered a colligative property?
A) vapor pressure B) boiling point C) conductivity D) freezing point
__A__37. Which of the following would be considered a strong electrolyte?
A) NaCl B) sugar C) acetic acid D) all of the choices
2 pts. 38. A) Write and balance an equation where methane (CH4) reacts with oxygen to
form carbon dioxide and water.
CH4 + 2O2 = CO2 + 2H2O
38. B) Give an example of a product of the reaction. CO2 or H2O
38. C) Which reactant is the oxidizing agent? O2
1.5 pts 39. Consider the following reaction.
4HCl + MnO2 = Cl2 + 2H2O + MnCl2
If MnO2 is defined as the oxidizing agent, what is the ..
Reducing agent? HCl
Substance being oxidized? HCl
Substance being reduced? MnO2
1.5 pts 40. NaHCO3 solution and HCl solution react together to form carbon dioxide, water
and NaCl solution. Write 3 balanced chemical equations to represent this reaction – a
“molecular”, a total ionic and a net ionic. Include the descriptors of (aq), (s), (g), etc as
appropriate.
NaHCO3(aq) + HCl(aq) = CO2(g) + H2O(l) + NaCl(aq)
All (aq) ionize/dissociate
Na+(aq) + HCO3- (aq) + H+(aq) + Cl-(aq) = CO2(g) + H2O(l) + Na+(aq) + Cl-(aq)
Cancel common terms
HCO3- (aq) + H+(aq) = CO2(g) + H2O(l)
2 pts 41. Consider two gases at the same temperature – He with an atomic mass of 4 and O2
with a mass of 32. Part of the kinetic molecular theory states that all gases have the same
kinetic energy at a given temperature. How is this possible since these gases differ so
greatly in mass? (one or two sentences should suffice.)
KE is a product of both mass and velocity. Since the mass of He is smaller its velocity is
greater.
2 pts 42. Match each reaction below as A) combination/synthesis B) decomposition C)
single displacement D) double displacement E) redox F) non-redox. Each equation will
have two correct answers.
_DF________AgNO3 + NaCl = AgCl + NaNO3
_AE________C + O2 = CO2
_AE________2SO2 + O2 = 2SO3
_BF________CaCO3 = CaO + CO2
2 pts 43. Describe how a colloid is similar to a true solution and also how it is different
from a true solution. Two or three sentences should suffice.
Colloids are like true solutions in that they are both homogeneous. They are different in
the respect that true solutions are clear while colloids are turbid (cloudy). Could also have
said something about the particle size of colloids being larger.
Max points were 40.