Download CH 115 Exam 2 - UAB General Chemistry Supplemental Instruction

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CH 115 Exam 2
Multiple Choice (5 percent each, no partial credit)
  Assume the chemical equations on this exam are NOT balanced unless stated otherwise.  
1. Balance the equation and give the
stoichiometric coefficient for HCl
KClO3 + HCl → KCl + H2O + Cl2 + O2
a. 1
b. 3
c. 2
d. 4
e. 6
2. Classify the two reactions
X: Na3PO4 + AgNO3 → NaNO3 + AgPO4
Y: Ca(HCO3)2 → CaO + H2O + CO2
Reaction X
Reaction Y
a. Decomposition Combination
b. Exchange
Decomposition
c. Displacement
Decomposition
d. Combination
Displacement
e. Exchange
Displacement
3. For complete combustion of hydrocarbons
which statements are true?
X. One reactant must be O2(g)
Y. One of the products is CO2(g)
Z. The reaction is an exchange reaction
a. X only
b. Z only
c. Y and Z
d. X and Z
e. Y only
4. If 45.5 g of NH3 and 90.3 g of O2 produce
32.9 g of H2O, find the percent yield?
4 NH3 + 3 O2 → 2 N2 + 6 H2O
a.
b.
c.
d.
e.
21.6%
68.4%
36.4%
64.7%
45.6%
5. What is the theoretical yield of PbCl2 from
the equation below given 14.8 g of KCl and
51.2 g of Pb(NO3)2?
KCl + Pb(NO3)2 → KNO3 + PbCl2
a. 43.0 g
b. 55.2 g
c. 21.5 g
d. 27.6 g
e. 33.0 g
6. The reaction below yields 86.7% MgO.
Given 34.5 g of MgCO3 calculate the actual
yield.
MgCO3(s) → MgO(s) + CO2(g)
a. 16.5 g
b. 29.9 g
c. 14.3 g
d. 15.6 g
e. 18.0 g
7. Which are precipitation reactions?
X. Na3PO4(aq) + CrCl3(aq)
Y. Fe(ClO3)2(aq) + NaOH(aq)
Z. NH4NO3(aq) + Mg(CH3COO)2(aq)
a. X only
b. Y only
c. Y and Z
d. X and Y
e. X and Z
8. What is the oxidation number for each C
atom in C2O42-?
a. +2
b. 0
c. +4
d. +3
e. +6
9. Which statements are false?
X. Strong electrolytes are compounds that
dissolve completely to form ions
Y. Strong acids are weak electrolytes
Z. Most molecular compounds are
electrolytes
a. Z only
b. X andY
c. X and Z
d. Y only
e. Y and Z
10. Which are weak acids with strong bases?
X. HCN(aq) + NH3(aq)
Y. HCOOH(aq) + NaOH(aq)
Z. H2CO3(aq) + LiOH(aq)
a. Y and Z
b. X only
c. Y only
d. X and Z
e. Z only
11. Which statements about the following
reaction are false?
N2(g) + O2(g) → 2 NO(g)
X. This is a decomposition reaction
Y. This is a redox reaction
Z. This is a combustion reaction
a. Y only
b. X and Y
c. X only
d. X and Z
e. Y and Z
12. Identify the reducing agent and oxidizing
agent
2 CO2 + 5 Cl2 → 2 CCl4 + 2 ClO2
Reducing agent
a. Carbon
b. Carbon
c. Chlorine
d. Chlorine
e. Oxygen
Oxidizing agent
Chlorine
Oxygen
Chlorine
Oxygen
Carbon
13. Which statements are true about the
following reaction?
Na2CO3(s) + HCl(aq) → NaO + CO2 + H2O
A. This is a gas-forming reaction
B. The CO2 comes from the rapid
decomposition of H2CO3
C. The reaction is already balanced
a. Z only
b. X and Y
c. X only
d. Y only
e. X and Z
14. Which reactants would give a product
spontaneously?
X. CoCl2(aq) + Br2(l)
Y. NiSO4(aq) + Sr(s)
Z. Ca(s) + Ba(NO3)2(aq)
a. Y only
b. X and Y
c. X and Z
d. Y and Z
e. Z only
15. What volume of 0.400 M HCl(aq) do you
need to dissolve 12.0 g of CaCO3(s)?
a. Not enough information to answer
b. 599 mL
c. 300 mL
d. 10.9 mL
e. 822 mL
16. If you titrate 40.0 mL of NaOH(aq) with 45.0
mL of 0.335 M H2SO4(aq), what is the
concentration of NaOH(aq)?
a. 0.377 M
b. 0.754 M
c. 0.594 M
d. None of the others
e. 0.297 M
Fill-in-the-blanks (1 percent per blank, no partial credit)
Complete the chemical equation below
•
•
•
•
Balance the equation.
Include the correct phase for each compound.
Include the stoichiometric coefficient. Even if the coefficient is “1” you must write it to get
credit.
Formulas for the compounds must be correct to receive credit.
_1_ Na2CO3(aq) + _1_ NiCl2(aq)  _2_ _NaCl__ (aq)_ + _1_ _NiCO3___ (s)__
Write the net ionic equation for the reaction between H3PO4(aq) and NaOH(aq)
•
•
•
•
Be sure the net ionic equation is balanced (i.e. balance the chemical equation first).
Include the correct phase for each ion and compound.
Include the stoichiometric coefficient. Even if the coefficient is “1” you must write it to get
credit.
Ion formulas and charges must be correct to receive credit.
_1_ _H3PO4_ (aq)_ + _3_ _OH-___ (aq)_  _1_ _PO43 -_ (aq)_ + _3_ _H2O__ (l)__
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