Download Name: ______KEY__________________ Date: ______ CHM 130

Name: ______KEY__________________
Date: ________
CHM 130, Exam 3: Chapters 9, 10, 11, and 13 (and some of 14)
Show all work and clearly mark all answers for full credit.
16. (4 pts) “Joe” decides to throw 3.45 grams of solid sodium into a “friend’s” pool. How many moles of
sodium is this?
3.45 g Na x (1 mol / 22.99 g) = 0.150 mol Na
17. (6 pts) Calculate the grams of CO2 in an 79.8 liter container at STP.
79.8 L x (1 mol / 22.4 L) x (44.01 g / 1 mol) = 157 g CO2
18. (3 pts) Calculate the percent composition of aluminum in aluminum oxide (Al2O3).
Al: 2 x 26.98 = 53.96
O: 3 x 16.00 = 48.00
% Al = (mass of Al / total mass) x 100
% Al = (53.96 / 101.06) x 100 = 52.92 %
Total mass = 101.96 g/mol
_A__ 19. (4 pts) In the reaction P4 + 5 O2  2 P2O5, how many moles of diphosphorus pentoxide are
produced when 0.500 moles of O2 are used?
a. 0.200 mol
b. 0.500 mol
c. 1.25 mol
d. 2.50 mol
e. 5.00 mol
0.500 mol O2 x (2 mol P2O5 / 5 mol O2) = 0.200 mol P2O5
20. (8 pts) Silver nitrate and sodium sulfate solutions react to make silver chloride and sodium nitrate
according to the balanced equation below. How many grams of silver nitrate are needed to completely
react with 0.327 grams of sodium sulfate?
2 AgNO3 (aq) + Na2SO4 (aq)  Ag2SO4 (s) + 2 NaNO3 (aq)
0.327 g Na2SO4 x (1 mol Na2SO4 / 142.05 g) x (2 mol AgNO3 / 1 mol Na2SO4) x
(169.88 g AgNO3 / 1 mol) = 0.782 g AgNO3
_E__ 1. (5 pts) Which of the following describes properties of gases?
a. They are compressible.
b. They expand to fill a container.
c. They take the shape of a container.
d. The particles in a gas are far apart.
e. All of the above are true.
CHM 130, Leedy
Spring 2013
page 1 of 4
Name: ______KEY__________________
2. (6 pts) Convert 694 torr to units of a) atm, b) mmHg, and c) psi.
Date: ________
a. atm: 694 torr x (1 atm / 760 torr) = 0.913 atm
b. mm Hg: 694 torr x (760 mm Hg / 760 torr) = 694 mm Hg
c. psi:694 torr x (14.7 psi / 760 torr) = 13.4 psi
3. (6 pts) You have a 1.00 L bottle of gas (closed), with P = 0.444 atm and T = 295° C. If you raise the
temperature to 395oC, will the pressure
increase
or
decrease
(circle one)?
Calculate the new pressure. P1 / T1 = P2 / T2;
0.444 atm / (295 + 273) = P2 / (395 + 273)
P2 = 0.522 atm
4. (6 pts) A sample of helium at 35oC, a volume of 0.25 L, and a pressure of 515 mm Hg is compressed to
a volume of 0.50 L, will the pressure
increase
or
decrease
(circle one)?
Calculate the final pressure.
Use Boyle’s Law for a constant temperature case of the ideal gas law:
P1V1 = P2V2
P2 = (515 mmHg)(0.25 L) / ( 0.50 L )
P2 = 260 mm Hg (or 0.34 atm)
5. (6 pts) A 6.35 L sample of carbon monoxide is collected at 55oC and 0.892 atm. What volume will the
gas occupy at 1.05 atm and 21oC?
P1V1 / T1 = P2 V2 / T2
(0.892 atm * 6.35 L) / (55 + 273) = (1.05 atm * x ) / (21 + 273)
0.0172689 = 0.0035714 x
x = 4.85 L (3 or 4 sig figs)
6. (12 pts) True or False: Circle the appropriate letter for each statement below:
a.
T
F
Liquids have a constant shape and constant volume.
b.
T
F
London forces are the strongest type of intermolecular force.
c.
T
F
Intermolecular forces holding molecules together are weaker than chemical bonds.
d.
T
F
Nonpolar molecules will have Dipole-Dipole forces.
e.
T
F
Xe is predicted to have higher a boiling point than He.
f.
T
F
CHM 130, Leedy
H2 is predicted to have a higher vapor pressure than H2O.
Spring 2013
page 2 of 4
Name: ______KEY__________________
Date: ________
7. (4 pts) What is the strongest type of intermolecular force (London forces, Dipole-Dipole, or Hydrogen
Bond Forces) in:
CH4: ___London forces___
H2O: ___Hydrogen Bond Forces______
8. (4 pts) Use the intermolecular force types of CH4 and H2O from the question above to determine the
following properties below.
a. Higher vapor pressure: __CH4___
b. Higher boiling point: __ H2O ____
c. Stronger surface tension: __H2O__
d. Higher viscosity: __ H2O ___
9. (6 pts) What holds the following together? Your choices are nonpolar covalent bond (NPC), polar
covalent bond (PC), ionic bond (I), London forces (LDF), Dipole-Dipole forces (DD), and Hydrogen
Bond Forces (HBF).
a. __PC_ N and O atoms in NO2.
b. _HBF_ The molecules in ammonia.
c. _NPC_ Chlorine atoms in Cl2.
d. __I__ Li and Cl ions in a solid.
e. _LDF_ Cl2 molecules in a gas.
f. _DD__ Two CH2F2 molecules.
_A__ 10. (5 pts) Which one of the following is an example of a metallic solid?
a. Mg (s)
b. CaCl2 (s)
c. CO2 (s)
d. P4 (s)
11. (6 pts) The graph to the right represents a
temperature versus heat energy plot for a pure
substance. Answer the following questions.
a. What letter represents pure gas? _E___
b. What phase changes occur at letter B?
__melting/freezing___________
c. What is the temperature of the boiling
point of this substance? __60oC_____
d. What letter represents pure solid? _A__
12. (8 pts) Complete the following table by determining if each solute will or will not mix with each
solvent. Your choices for each combination are miscible, immiscible, soluble, or insoluble.
Solvents ()
ZnSO4 (s)
CH2F2 (l)
S8 (s)
Br2 (l)
H2O (l)
soluble
miscible
insoluble
immiscible
CCl4 (l)
insoluble
immiscible
soluble
miscible
CHM 130, Leedy
Spring 2013
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Name: ______KEY__________________
__C_ 13.
a.
b.
c.
d.
Date: ________
(5 pts) A nitric acid solution that is 70.0% HNO3 by mass contains
70.0 g of HNO3 and 100.0 g water.
70.0 mol HNO3.
70.0 g HNO3 and 30.0 g water.
70.0 g HNO3 and 70.0 g water.
14. (5 pts) An oven cleaning solution is 40.0 % by mass of NaOH. If one jar of this product contains 454
grams of solution, how many grams of NaOH does it contain? Show all work.
Mass solute / mass solution x 100 = (x g / 454 g) x 100 = 40.0%
x = 454 g * 0.400 = 181.6 g = 182 g
15. (5 pts) If 160.20 grams of NH4Cl is dissolved in 4.00 L of water, what is the concentration (molarity)
of the solution?
160.20 g x (1 mol / 53.5 g) = 2.994 mol NH4Cl / 4.00 L = 0.749 M
_C__16. (5 pts) What is the term for a substance that donates a proton in an acid-base reaction?
a. Arrhenius acid
b. Arrhenius base
c. Bronsted-Lowry acid
d. Bronsted-Lowry
base
17. (2 pts) In the following reaction, which reactant is a Bronsted-Lowry base? Circle your answer.
NH3(aq) + H2O (l)
NH4+ (aq)
+ OH- (aq)
18. (4 pts) What is the pH of a solution with [H+] = 1.0 x 10-3 M? __3.0____________
Is this solution acidic, basic, or neutral? ___acidic__________
CHM 130, Leedy
Spring 2013
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