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Answer Key
Chem 400 Mid-Term Exam 3 – Multiple Choice
You have 45 minutes to complete this section.
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Choose the one alternative (a-e) that best answers each question in this section.
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Equations and constants
K = °C + 273 K
PV = nRT
STP = 0 °C and 1 atm
R = 0.0821 L·atm/mol·K
1 mL = 1 cm3
P = gdh
R = 8.314 J/mol·K
1 mL water = 1 g
ln P(atm) =
∆H vap § 1 1 ·
¨
− ¸
R ¨© T B T ¸¹
H2O vapor pressure = 16.5 mmHg at 19°C, 18.7 mmHg at 21°C, 21.1 mmHg at 23°C
1 atm = 760 mmHg = 1.01325 x 105 Pa = 14.7 psi
P1V1 P2V 2
=
T1
T2
Solubility A PA
=
Solubility B PB
Ptotal = P1 + P2 + P3 + …..
PA = PA X A
molality = moles / kg solvent
π = iMRT
2 

 P + n a (V − nb ) = nRT

V 2 

q = mc∆T
q = n ∆Hv
∆Tf = i Kf cm
mass % = mass solute / mass solution
Effusion rate A
∝
Effusion rate B
q = n ∆Hf
molar mass B
molar mass A
solubility = kHP
Molarity = moles / L solution
mole fraction A = moles A / total moles
1. Which of the following statements about the solution process is/are true?
i. Gases are less soluble in liquids as their partial pressure increases
ii. Solids break up entirely before solvation occurs
iii. If more solid is added to a saturated solution, some of the dissolved solid crystallizes out of solution
a) i only
b) i and iii
c) ii only
d) All of them
e) None of them
2. Which of the following statements about real and ideal gases is true?
a) In real gases, the actual volume of the gas molecules is a significant fraction of the volume occupied by the gas.
b) Collisions of real gas molecules are always inelastic.
c) Intermolecular forces can decrease the expected pressure of the real gas compared to an ideal gas.
d) Real gases have significantly greater densities than ideal gases.
e) Real gases are more like ideal gases at lower temperatures.
3. What is the name of the point at which a substance's gas, liquid and solid phases can all exist simultaneously?
e) fusion point
a) Convergence point b) melting point
c) critical point
d) triple point
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4. If a sample of nitrogen gas is heated in a sealed container of fixed volume from 25 to 250°C, the value of which of the
following quantities will remain unchanged?
a) The pressure of the gas.
b) The average kinetic energy of the gas molecules.
c) The density of the gas.
d) The distribution of molecular speeds
e) The collision frequency of gas molecules with each other.
5. Which of the following would indicate very strong intermolecular forces?
a) Low boiling point
b) Low melting point
c) Low vapor pressure
d) Low viscosity
e) Low ∆Hvap
6. What is the coefficient of H+ when you balance the following REDOX equation;
H+ + Cl + Sn + NO3 SnCl62 + NO2 + H2O
a) 2
b) 4
c) 6
d) 8
e)10
7. Neon atoms do not combine to form Ne2 molecules, yet neon atoms can be liquified at low temperatures, due to which
of the following intermolecular forces?
a) Hydrogen bonding b) dipole-dipole
c) London dispersion d) metallic
e) covalent
8. Which of the following statements is true, concerning equal volumes of the gases dinitrogen monoxide,N2O, and
propane, C3H8, at the same temperature and pressure?
a) They have the same number of atoms
b) They have the same number of molecules
c) They have the same density
d) More than one of the preceding statements is correct
e) None of the preceding statements is correct
9. All the following reactions are single-displacement or double-displacement reactions EXCEPT
Cu(s) + FeSO4(aq).
a) CuSO4(aq) + Fe(s) →

b) Cu(s) + 2AgNO3(aq) →
Cu(NO3)2(aq) + 2Ag(s).

c) 2Na(s) + 2H2O(l) →
2NaOH(aq) + H2(g).

d) CH4(g) + O2(g) →
CO2(g) + H2O(l).

ZnCl2(aq) + Fe(s).
e) Zn(s) + FeCl2(aq) →

10. All the following compounds are soluble in water EXCEPT
b) FeCl2
c) NaCl
a) Hg2Cl2
d) ZnCl2
e) BaCl2
11. When ammonium nitrite undergoes decomposition, only gases are produced. The equation is;
N2(g) + 2H2O(g)
NH4NO2(s) →

What is the total volume of gases produced at 273 K and 1.00 atm pressure when 192 g of ammonium nitrite
decomposes?
b) 7 x 22.4 L
c) 6 x 22.4 L
d) 3 x 22.4 L
e) 22.4 L
a) 9 x 22.4 L
12. Which of the following compounds is expected to have the HIGHEST boiling point?
c) CH3CH2CH2CH3 d) CH3Cl
a) CH3OCH3
b) CH3CH2OH
2
e) CH3CH2CH3
13. In the accompanying phase diagram, a SOLID can be present at combinations of temperature and pressure
corresponding only to the points;
a) A, C, D, G
b) C, D, E, G
c) A, C
d) A, B, C, G
e) A, C, D, F
14. Which of the following solutes dissolved in 1.0 kg of water would be expected to provide a solution with the
HIGHEST boiling point?
b) 0.10 mole CsF
c) 0.10 mole HNO3 d) 0.10 mole NaCl
e) 0.10 mole Na2SO4
a) 0.10 mole HC2H3O2
15. When a liquid is boiling, which of the following statements is true?
i. The temperature stays constant during the change of state
ii. No energy is absorbed by the liquid during the change of state
iii. The temperature changes because bonds are being broken during the boiling process
b) ii and iii
c) i and ii
d) i, ii, and iii
a) i only
e) none of them
16. Which of the following metals reacts with aqueous FeSO4? (Partial Activity Series: Fe > Co > (H) > Cu > Ag)
a) Cu
b) Ag
c) Co
d) more than one of them
e) none of them
17. What is the mass of 2.50 L of sulfur dioxide gas, SO2, at STP?
c) 1.14 g
d) 0.875 g
e) 56.0 g
a) 25.6 g
b) 7.15 g
18. If 0.019 mol of hydrogen gas is collected over water at 50.0 °C and 763 mm Hg, what is the volume of dry gas? (The
vapor pressure of water is 92.5 mm Hg at 50.0 °C)
b) 0.078 L
c) 0.088 L
d) 0.50 L
e) 0.57 L
a) 1.0 x 10-4 L
19. Which of the following is/are true?
i. Arrhenius acids put H+ ions into a solution
ii. Bronsted-Lowry bases are the same as Arrhenius bases
iii. Twice as many moles of H2SO4 are needed to neutralize a given amount of NaOH
a) i only
b) ii and iii
c) i and ii
d) i, ii, and iii
e) none of them
20. What is the mass of zinc acetate (183.49 g/mol) dissolved in 0.200 L of 0.500 M Zn(C2H3O2)2 solution?
d) 36.7 g
e) 91.7 g
a) 12.4 g
b) 1.83 g
c) 18.3 g
21. If a 25.0 mL sample of sulfuric acid is titrated with 50.0 mL of 0.200 M potassium hydroxide to a phenolphthalein
endpoint, what is the molarity of the acid?
H2SO4(aq) + 2 KOH(aq) → K2SO4(aq) + 2 H2O(l)
d) 0.300 M
e) 0.150 M
a) 0.400 M
b) 0.100 M
c) 0.200 M
22. An unknown solvent has a normal boiling point of 82.2°C and its heat of vaporization is 12.9 kJ/mol. What is its
vapor pressure at room temperature (25°C)?
d) 110 mmHg
e) 16.1 mmHg
a) 759 mmHg
b) 648 mmHg
c) 329 mmHg
23. What is the molar mass of a gas that effuses 1.9 times slower than CH4?
a) 58 g/mol
b) 73 g/mol
c) 30 g/mol
d) 130 g/mol
e) 8.4 g/mol
24. Pure benzene freezes at 5.5°C. 30.0 g of iodine (I2) is dissolved in 300. g of benzene and the solution is frozen. At
what temperature did the solution freeze? (Kf = 5.1 °C/m for benzene)
c) 5.5°C
d) 7.5°C
e) 9.5°C
a) 1.5°C
b) 3.5°C
25. An unknown metal has a cubic face-centered unit cell and its density is 254 amu/unit cell. What is the metal?
b) Zn
c) Au
d) Na
e) Al
a) Cu
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