Name:

Name of your Discussion TA:

o Elisabeth Dooley
o Abigail Erickson
o Kenneth Osoro
o Taylen Sewell
CHEM 1020-02 – Fall 2023 – Practice Exam 2
100 Points – 10% of your grade – None of the exams will be dropped
Wednesday, 3/8/23, 5:00 – 7:00 p. m.
Location:
Last Name A – K: CR 129
Last Name L – Z: CR 222

Exam 2. Covers Chapters 4, 5 and Sections 6.1 – 6.4 in Chapter 6.

Section I. Most questions are multiple choice. You may choose to show your work for partial credit.
Section II. You must show your work for full credit.
Bonus Section: These points you can keep!
You may tear-off the last two sheets and use them as scratch paper.

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 Section I
30 × 2 = 60 points

1. What are the correct coefficients (reading from left to right) when the chemical equation is balanced?

_Co(NO3)3 (aq) + _(NH4)2S (s) → _Co2S3 (s) + _NH4NO3 (aq)

a) 1, 2, 1, 2
b) 1, 3, 2, 2
c) 2, 3, 3, 6
d) 2, 3, 1, 6
e) 2, 6, 3, 2

2. How many moles NO2 form when 15.2 g N2O5 completely reacts?
2 N2O5 (g) → 4 NO2 (g) + O2 (g)
a) 0.422 mol
b) 0.493 mol
c) 0.211 mol
d) 0.352 mol
e) 0.281mol

3. Sulfuric acid dissolves aluminum metal according to the reaction:

2 Al (s) + 3 H2SO4 (aq) → Al2(SO4)3 (aq) + 3 H2 (g)
Suppose you want to dissolve an aluminum block with a mass of 15.2 g. What minimum mass of H2SO4
(in g) do you need?
a) 67.3 g
b) 37.9 g
c) 43.3 g
d) 103 g
e) 82.9 g

4. What is the limiting reactant if the following reaction is carried out with 1 mol Al (s) and 1 mol O2 (g)?
4 Al (s) + 3 O2 (l) → 2 Al2O3 (s)
a) Al (s)
b) O2 (l)

5. Balance the following reaction and calculate the theoretical yield of SiCl4 (l) in moles formed when the
reaction is carried out with 4.0 mol Si (s) and 7.0 mol Cl2 (g).
Si (s) + Cl2 (g) → TiCl4 (l)

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 a) 7.0 mol
b) 3.5 mol
c) 4.0 mol
d) 3.0 mol
e) 11 mol

6. What products are formed when CS2 undergoes combustion with excess O2?
a) CO2 and H2O
b) SO2 and H2O
c) CO2 and H2SO4
d) CO2 and SO2
e) CO2 and S8

7. Which products are formed when Na (s) reacts with H2O (l)?
a) Na+ (aq), OH− (aq), and H2 (g)
b) Na+ (aq), OH− (aq), and O2 (g)
c) Na+ (aq), O− (aq), and H2 (g)

8. Write a balanced equation for the reaction between lithium metal and chlorine gas.
Li (s) + Cl2 (g) →

9. Which of the following solutions contains the highest number of moles of Cl− ions?
a) 0.556 L of a 2.3 M KCl solution
b) 2.0 L of a 0.80 M KCl solution
c) 1.8 L of a 0.75 M KCl solution
d) 0.114 L of a 1.85 M KCl solution
e) 1 L of a 1 M KCl solution

10. A stock solution has a concentration of 2.25 M. If you dilute 547 mL of the solution to 3.35 L, what is
the concentration of the new solution?
a) 0.412 M
b) 2.43 M
c) 0.0409 M
d) 0.367 M
e) 27.2 M

11. Which of the following reaction does not form a precipitate?

a) NiCl2 (aq) + (NH4)2S (aq) →

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 b) KOH (aq) + 2 NH4Cl (aq) →
c) 3 Mn(NO3)2 (aq) + 2 Na3PO4 (aq) →
d) CaCl2 (aq) + Hg2(NO3)2 (aq) →
e) (NH4)2SO4 (aq) + BaCl2 (aq) →

12. Which is a weak acid?

a) HC2H3O2
b) NH3
c) H2SO4
d) HNO3
e) H3PO4

13. Which compound is insoluble?

a) CaS
b) Mg3(PO4)2
c) Li2CO3
d) NH4Cl
e) AgNO3

14. Complete and balance the following reaction. Will this reaction proceed in the forward direction?
(NH4)SO4 (aq) + BaCl2 (aq) →

15. Write the balanced complete ionic equation for the following reaction.
Na3(PO4) (aq) + NiCl2 (aq) → Ni3(PO4)2 (s) + NaCl (aq)

16. What spectator ions are involved in the reaction described in the question above?
a) Na+ (aq) and PO43− (aq)
b) PO43− (aq) and Ni2+ (aq)
c) Na+ (aq) and Cl− (aq)
d) Na+ (aq) and Ni2+ (aq)
e) PO43− (aq) and Cl− (aq)
17. Write the net ionic equation for the reaction described in question 16.

18. Write net ionic equations for each acid-base equation.

HBr (aq) + NaOH (aq) → H2O (l) + NaBr (aq)

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 HC2H3O2 (aq) + NaOH (aq) → H2O (l) + NaC2H3O2 (aq)

19. What intermediate decomposes to form a gaseous product in the following gas-evolution reaction?
2 HClO4 (aq) + Li2CO3 (aq) → 2 LiClO4 (aq) + H2O (l) + CO2 (g)

20. Complete and balance the following combustion reaction.

C3H6 (g) + O2 (g) →

21. Which of the following statements is correct?

a) HC2H3O fully ionizes in aqueous solution forming H+ (aq) and C2H3O (aq).
b) Aqueous solutions of sugar molecules conduct electricity.
c) Precipitation reactions involve transfer of electrons from one reactant to another.
d) Gas evolution reactions require one of the reactants to be water insoluble.
e) Reactions involving O2 (g) may both be redox and combustion reactions.

22. What is the oxidation state of Cl in ClO−?

a) +1
b) +2
c) +3
d) −1
e) −2

23. Which redox reaction occurs spontaneously in the forward direction?

Fe (s) + Mn2+ (aq) → Fe2+ (aq) + Mn (s)
3 Pb2+ (aq) + 2 Al (s) → 2 Al3+ (aq) + 3 Pb (s)

24. Suppose you wanted to cause Ni2+ ions to come out of solution as solid Ni. Which metal could you use
to accomplish this?
a) Sn (s)
b) Fe (s)
c) Cu (s)
d) Pb (s)
e) Au (s)

25. Consider this redox reaction:

Mn (s) + 2 H+ (aq) + 2 Cl− (aq) → Mn2+ (aq) + 2 Cl− (aq) + H2 (g)
Which of the following is the reducing agent?
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 a) Mn (s)
b) H+ (aq)
c) Cl− (aq)
d) H2O (l)
e) Mn2+ (aq)

26. The weather report states that the pressure is 30.44 inches Hg. Convert this to psi. (1 in = 25.4 cm).
a) 15.0 psi
b) 15.9 psi
c) 0.589 psi
d) 0.497 psi
e) 1.04 psi

27. A diver at a depth of 111 ft at pressure 2.74 atm exhales bubbles of air with a combined volume of 38.0
mL. What will be the volume of the bubbles when they reach the surface? The pressure at the surface
is 1 atm.
a) 24.1 mL
b) 56.2 mL
c) 83.1 mL
d) 92.1 mL
e) 104 mL

28. If a certain amount of gas occupies a volume of 25.5 mL at 56.6 ºC, what volume will this sample of
gas occupy at 33.5 ºC if the pressure is kept constant?
a) 43.1 mL
b) 18.7 mL
c) 23.7 mL
d) 36.4 mL
e) 15.1 mL

29. Consider a large balloon has a volume of 8.34 L containing 0.456 mole of a gas. If the pressure and
temperature of the balloon are kept constant, what would the new volume of the balloon be if 0.222
moles of the gas is removed from it?
a) 2.67 L
b) 4.28 L
c) 4.56 L
d) 4.17 L

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 e) 2.19 L

30. A gas is in a constant volume container at a pressure of 0.923 atm. What will be its pressure if you raise
its temperature from 22.5 C to 35.5 C?
a) 0.632 atm
b) 0.981 atm
c) 0.912 atm
d) 0.964 atm
a) 1.13 atm
Section II
5 × 8 = 40 points
31. Iron(II) sulfide reacts with hydrochloric acid according to the reaction:
FeS (s) + 2 HCl (aq) → FeCl2 (s) + H2S (g)
A reaction mixture initially contains 0.423 mol FeS and 0.652 mol HCl. Once the reaction has occurred
as completely as possible, what amount (in mol) of the excess reactant remains?

32. Many computer chips are manufactured from silicon, which occurs in nature as SiO 2. When SiO2 is
heated to melting, it reacts with solid carbon to form liquid silicon and carbon monoxide gas. In an
industrial preparation of silicon, 155.8 kg of SiO2 reacts with 78.3 kg of carbon to produce 66.1 kg of
silicon. Determine the limiting reactant, theoretical yield, and percent yield for the reaction.

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33. A 30.00-mL sample of an unknown H3PO4 solution is titrated with a 0.100 M NaOH solution. The
equivalence point is reached when 26.38 mL of NaOH solution is added. What is the concentration of
the unknown H3PO4 solution? The neutralization reaction is:
H3PO4 (aq) + 3 NaOH (aq) → 3 H2O (l) + Na3PO4 (aq)

34. Which of the reactants is the oxidizing agent in the following reactions?
a) 2 Au (s) + 2 BrF3 (l) + 2 KF (s) → Br2 (l) + 2 KAuF4 (s)
b) CH4 (g) + Br2 (g) → CH3Br (g) + HBr (g)
c) F2 (g) + Br2 (g) → 2 BrF (s)
d) C2H4 (g) + H2O2 (aq) → C2H4O (g) + H2O (l)

35. A sample of gas has a mass of 38.8 mg. Its volume is 0.224 L at a temperature of 55 °C and a pressure
of 886 torr. Find the molar mass of the gas.

Bonus Section
1 × 4 = 4 points
36. Match the reactions to the correct type.
a) NiCl2 (aq) + AgNO3 (aq) → 2 AgCl (s) + Ni(NO3)2 (aq)
b) HBr (aq) + KOH (aq) → H2O (l) + KBr (aq)
c) Mg (s) + Br2 (l) → MgBr2 (s)
d) Na2CO3 (aq) + 2 HCl (aq) → H2O (l) + CO2 (g) + 2 NaCl (aq)

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Molarity of Solution
𝑚𝑜𝑙
M=
𝑣𝑜𝑙𝑢𝑚𝑒 𝑖𝑛 𝐿

Gay-Lussac’s Law:
P1T2 = P2T1
𝐿∙𝑎𝑡𝑚
R = 0.08206 𝑚𝑜𝑙∙𝐾

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