EXAM 2 PRACTICE QUESTIONS KEY
NOTE- THIS IS ONLY A SELECTION OF POSSIBLE TYPES OF QUESTIONS: REFER
TO THE EXAM 2 REVIEW GUIDELINES FOR THE LIST OF LEARNING TARGETS.
There will likely be other questions on the exam not shown here, e.g., Net Ionic Equations, etc.
1. Balance the following chemical equations:
a.
2 C8H18 + 25 O2 
16 CO2 +
b.
2 B5H9 + 12 O2 
5 B2O3+
c.
S8 +
4 Cl2 
18 H2O (nothing this hard on exam!)
9 H2O
4 S2Cl2
2. Change these word equations into formula equations and balance them
a. Lithium metal reacts with water to produce hydrogen gas and aqueous lithium
hydroxide
Li(s) + H2O(l)  H2(g) + LiOH (aq)
b. Copper metal placed in a zinc (will give you charge as 2+) nitrate solution produces
aqueous copper (I) nitrate plus zinc metal.
2 Cu(s) + Zn(NO3)2(aq)  2 CuNO3(aq) + Zn (s)
a.
b.
c.
d.
3. A gas sample is collected in a balloon. What happens to the density of the gas sample as the sample is
heated?
decreases
increases
does not change
could increase or decrease, depending on how much it was
heated
4. 2500 liters of oxygen gas is produced at 1.00 atm of pressure. It is to be compressed and stored in a
a.
b.
c.
d.
20.0 liter cylinder. If temperature is constant, calculate the pressure of the oxygen in the cylinder.
125 atm
4.0 atm
80.0 atm
8.00 atm
5. A balloon has a volume of 5.00 liters of 22C and 1.00 atmosphere of pressure. What will be the
balloon's volume in liters if the pressure is increased to 3.00 atmospheres at 22C?
a.
1.67
b.
0.600
c.
1.30
What volume in liters is occupied by 8.22 g of SO2 gas confined at a pressure of 1200 torr (1.578atm) at
75.0C?
R = 0.0821 liter atm/mol K
a.
b.
c.
d.
0.499
4.22  101
2.32
32.1
a.
b.
c.
d.
6. A mixture of helium, argon and krypton is made and stored in a cylinder at a total pressure of 2.80 atm
(2128 torr). The partial pressure of helium is 900 torr (1.184 atm), and that of argon is 250 torr (0.329
atm). What is the partial pressure of krypton in the mixture?
1.18 atm
1.51 atm
1150 torr (1513 atm)
978 torr (1.29 atm)
a.
b.
c.
d.
7. When a liquid sample is taken from sea level to a higher elevation, what happens to the external
(atmospheric) pressure on the liquid and the boiling point of the liquid?
both decrease
both increase
pressure goes down, but boiling point goes up
pressure goes up, but boiling point goes down
8. The vapor pressure of a liquid
a.
b.
c.
d.
decreases with increasing temperature
is independent of temperature
is equal to one atmosphere at the normal
boiling point
cannot be measured
c.
d.
9. What is the most likely possible cause for water to have a high specific heat and ability to dissolve
many ionic compounds ?
its molar mass
its molecular structure causing hydrogen
bonding interactions
that it’s made from two gases
its ionic bonds
a.
b.
c.
d.
10. Carbon tetrachloride, CCl4, 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 CCl4 molecule?
It is ionic.
It is polar.
It is nonpolar.
Nothing can be inferred.
a.
b.
a.
b.
c.
d.
11. What volume of a 10.00% (w/v) solution of sugar is needed to provide 2.00 g of sugar?
0.200 liter
1.00 mL
20.0 mL 2.00 g solute/20.0 mL soln x 100
5.00 mL
a.
12. How many grams of solid KCl are needed to prepare 250 mL of 0.235 M solution?
9.32
b.
31.3
c.
15.6
d.
4.38
a.
b.
c.
d.
13. How many mL of 6.00 M HCl are needed to prepare 1500 mL of 0.200 M HCl solution?
1.80  104
125
2.00  103
50.0
14. Which of the following pass through both osmotic and dialysis membranes?
solvent molecules
large molecules
small molecules that are larger than solvent
molecules
more than one response is correct
d.
a.
b.
c.
a.
b.
c.
d.
15. Express the following concentration of solution in terms of molarity: 3.00 L of solution contains 1.75
mol of solute.
5.25 M
0.583 M (1.75 mol/3.00 L soln)
1.71 M
too little information to know
a.
b.
c.
d.
16. One test to determine if a mixture is a true solution or a colloid is ____.
physical state of the mixture
boiling point elevation
light scattering
color
17. The concept of entropy
a.
b.
c.
d.
is employed to explain how energy can be
stored
is employed to explain how an exothermic
reaction can become endothermic
is employed as an indicator of disorder in a
system
explains why most chemical reactions are
endothermic
a.
b.
c.
d.
a.
b.
c.
d.
18. Which of the following states of matter generally has the lowest entropy?
a crystalline solid
a liquid
a gas
two of the three have virtually the same
entropy
19. The reaction conditions for a specific reaction, , are correct, but the reaction does not occur. What
could be the reason?
There are no collisions between the
molecules.
The collisions of the particles with the
container walls remove the required energy
because it is transferred to the container
molecules.
The orientation of the molecules with respect
to each other is not correct for the reaction to
occur.
There is more than one answer.
20. Catalyts can do which of the following:
a.
increase the amount of energy given off of an
exothermic reaction
lower activation energy
make a reaction proceed at a lower
temperature
there is more than one correct response (a and
b)
b.
c.
d.
21. The following question(s) refer to the following equilibrium in which all reactants and products are
gases:
CH4 + H2O  CH3OH + H2 + heat
Remove H2 from the mixture.
a.
b.
c.
d.
shifts left
shifts right
no effect
can shift to right or left
Cool the mixture.
a.
b.
c.
d.
shifts left
shifts right
no effect
can shift to right or left
22. Which method can be used to produce a timed-release medication?
a. The patient is given the medication in small doses over time, rather than one larger dose.
b. The patient is to take the medication two or three times a day.
c. The medication is provided in special capsules that are subdivided into smaller, pulverized portions of the
medicinal compound.
d. The medication compound is produced in very small amounts and each is coated with a material of varying
thickness
5. Complete and balance the equation for this single replacement reaction Zn forms a 2+ ion
sulfate ion is SO42-):
Zn +
H2SO4  Zn SO4 + H2
6. Complete and balance the equation for this double replacement reaction:
BeCl2 +
2 KOH  Be(OH)2 + 2 KCl
7. Complete and balance the equation for this combination reaction:
2 Na +
F2  2 NaF
8. Complete and balance the equation for this decomposition reaction:
2 H2O  2 H2 + O2
28. Provide the oxidation number for each atom in the polyatomic ion SO42Sulfur:_____+6_______
Oxygen: ___-2_________
29. CaSO4 is obtained by reacting 4.50g of Ca and 3.5g of H2SO4? (And which is the limiting
reactant?)
Ca (s) + H2SO4 (aq)  CaSO4 (aq) + H2 (g)
a. What is the theoretical yield of CaSO4 ?
b. What is the limiting reactant?
c. Is this a redox reaction—if so, what is reduced, what is oxidized. YES, Ca is
oxidized (0  2+. Loss of electrons, LEO), H is reduced
Theoretical Yld. (Molar Mass Ca= 40.08 g/mol
CaSO4 = 136.14 g/mol
Molar Mass H2SO4 =98.08 g/mol Molar Mass
From Ca: 4.50g /Molar Mass Ca x Mole Ratio x Molar Mass CaSO4 = 15.29 g
From H2SO4: 3.5 g same method as above = 4.86 g = THEORETICAL YIELD
H2SO4 LIMITING REACTANT
30. A gas occupies a volume of 250. mL at 5.25 atm pressure. When the pressure is reduced to
1.50 atm, what volume will the gas occupy (assuming constant temperature)?
875 mL
31. An expandable balloon contains 4500. L of He at 1.20 atm and 20C. The balloon rises to an
altitude of 10,000 feet, where the pressure is 0.600 atm and the temperature is 5C. What is
the volume of the balloon at this altitude?
8,540 L (pressure decreases by ½ so if temp constant volume should double, the slight temp
decrease causes the volume to decrease some)
32. How many grams of nitrogen gas will be needed to fill a balloon to a volume of 4.5 L at STP
(OoC, 1atm)
PV= nRT (1atm)(4.5 L) = n (0.0821 L atm/mol K)(273 K)
n = 0.20077….moles N2 (carry digits till end)
grams N2 = 0.20077.. moles x 28 g/mol N2 = 5.62 g N2
33. How many moles of KMnO4 are in 220 mL of 1.2 M KMnO4 solution?
1.2 mol/L x .220 L = 0.264 mol KMnO4
34. What volume of 12.0 M HCl is required to prepare 1.00 L of 3.00 M HCl?
.250 L or 250 mL of 12.0 M HCl, (then add 750 mL of water to get 1.00 L of 3.00 M HCl)
35. Given the equation:
CuSO4 + 2NaOH  Cu(OH)2 + Na2SO4
Calculate the amount of mL of 0.50 M NaOH solution that will react with 15 mL of 0.20 M
CuSO4 solution.
12 mL NaOH solution