Download 5 · Chemical Reactions

South Pasadena • Chemistry
Name
Period
Date
5 · Chemical Reactions
UNIT TEST
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PRACTICE
You may use a pencil, eraser, and scientific calculator to complete the test.
You will be given a periodic table and a solubility chart. No other resources are allowed.
You have fifty (50) minutes to complete this test, unless other arrangements have been made.
Please transfer your answers for questions in Sections 1 and 2 onto the Answer Document. Work for these
questions will not be graded. However, sufficient and appropriate work must be shown for the Free Response
questions in order to receive full credit.
SECTION 1: MATCHING. Use the following answer choices that best describe the reactions below. Answer
choices may be used once, more than once, or not at all. (1 point each)
(A) Single replacement
(B) Synthesis
(C) Decomposition
(D) Double Replacement
1. Zn (s) + 2 HCl (aq)  H2 (g) + ZnCl2 (aq)
2. Al2(SO4)3 (aq) + 3 BaCl2 (aq)  2 AlCl3 (aq) + 3 BaSO4 (s)
3. Zn (s) + 2 AgNO3 (aq)  2 Ag (s) + Zn(NO3)2 (aq)
4. CaCO3 (s)  CaO (s) + CO2 (g)
SECTION 2: MULTIPLE CHOICE. Select the best answer choice for each question. (2 points each)
5. In a chemical reaction the total mass of the
chemicals before the reaction and after the
reaction is
(A) equal.
(B) usually greater.
(C) usually smaller.
(D) sometimes greater and sometimes smaller.
6. Which one of the following reactions results in a
single product?
(A) decomposition reaction
(B) double replacement reaction
(C) single replacement reaction
(D) synthesis reaction
7. Which coefficients will balance this equation:
…C (s) + …SO2 (g)  …CS2 (ℓ) + …CO (g)
(A) 2, 1, 1, 2
(B) 3, 3, 1, 2
(C) 5, 2, 3, 2
(D) 5, 2, 1, 4
8. What is the coefficient in front of O2 when the
equation below is balanced using the lowest whole
number coefficients?
…NH3 (g) + …O2 (g)  …NO (g) + …H2O (g)
(A) 2
(B) 3
(C) 4
(D) 5
9. What is the coefficient for O2 in the equation for
the combustion of propane, C3H8?
(A) 2
(B) 3
(C) 4
(D) 5
10. How many grams HCl are needed to react with
3.25 g Al according to the following balanced
equation:
2 Al (s) + 6 HCl (aq)  2 AlCl3 (aq) + 3 H2 (g)
[MM: 27.0
36.5
133
14. Which of the following would be a precipitate
formed when solutions BaCl2 and K2SO4 are
combined?
(A) BaSO4 only
(B) KCl only
(C) Both BaSO4 and KCl
(D) No precipitate would form
15.
2.02 ]
(A) 2.20
(B) 4.05
(C) 4.39
(D) 13.2
11. How many grams of carbon are needed to react
completely with 75.2 g SiO2 according to the
balanced equation:
SiO2 (s) + 3 C (s)  SiC (s) + 2 CO (g)
[MM:
60.0
12.0
44.1
28.0 ]
(A) 15.0 g
(B) 20.5 g
(C) 45.1 g
(D) 61.5 g
12. Solutions of AgNO3 and CaCl2 are mixed and a
precipitate forms. What is the correct formula of
the precipitate?
(A) AgCl
(B) AgCl2
(C) Ca(NO3)2
(D) CaNO3
13. The following compounds are formed during
double replacement reactions. Which one would
be classified as a precipitate?
(A) Cu(OH)2
(B) KNO3
(C) Mg(C2H3O2)2
(D) NH4Cl
Zn + Ni2+  Ni + Zn2+
In the reaction above, which of the following
represents the oxidation half-reaction?
(A) Ni  Ni2+ + 2 e–
(B) Ni2+ + 2 e–  Ni
(C) Zn  Zn2+ + 2 e–
(D) Zn + 2 e–  Zn2+
16. Which of the following represents the products
when Mg is placed in HCl?
(A) H and MgCl
(B) H2 and MgCl2
(C) MgH2 and Cl2
(D) MgHCl
17. 3 Sr (s) + 2 FeCl3 (aq)  2 Fe (s) + 3 SrCl2 (aq)
Which of the following is true about the reaction
above?
(A) Sr is oxidized from Sr to Sr2+.
(B) Sr is oxidized from Sr2+ to Sr.
(C) Sr is reduced from Sr to Sr2+.
(D) Sr is reduced from Sr2+ to Sr.
18.
Mg (s) + O2 (g)  MgO (s)
In the reaction above, Mg is
it is
.
(A) Gaining … oxidized
(B) Gaining … reduced
(C) Losing … oxidized
(D) Losing … reduced
electrons, so
SECTION 3: FREE RESPONSE. Show all your work to receive full credit.
19. Consider the following process: Solutions of calcium nitrate and sodium sulfate are combined.
(a) Classify the reaction (circle one): (1 point)
[ Combustion | Decomposition | Double replacement | Single replacement | Synthesis ]
(b) Write the balanced chemical equation with the lowest whole-number coefficients. (3 points)
(c) Identify the precipitate(s), if any. (2 points)
20. Consider the following process: Nickel metal is placed in a solution of cupric chloride.
(a) Classify the reaction (circle one): (1 point)
[ Combustion | Decomposition | Double replacement | Single replacement | Synthesis ]
(b) Write the balanced chemical equation with the lowest whole-number coefficients. (3 points)
(c) Which element is oxidized? (1 point)
reduced? (1 point)
21. Consider the following process: Methanol (CH3OH) is burned in air.
(a) Classify the reaction (circle one): (1 point)
[ Combustion | Decomposition | Double replacement | Single replacement | Synthesis ]
(b) Write the balanced chemical equation with the lowest whole-number coefficients. (3 points)
(c) If 1.5 mol of CO2 are produced, how many moles of CH3OH were burned? Show work. (2 points)
22. The compound boron carbide, B4C, is one of the hardest materials known, and used in tank armor, bulletproof
vests, and other industrial applications. It is prepared according to the reaction represented by the
unbalanced equation below:
… B2O3 (s) + … C (s)  … B4C (s) + … CO (g)
(a) Write the balanced equation below. (2 points)
(b) Calculate the molar mass of boron carbide, B4C. (2 points)
(c) How many moles of B4C can be produced if 0.550 moles B2O3 is used? (2 points)
(d) What is the mass of B4C formed if 14.5 L of CO are also produced at STP? (4 points)
(e) How many atoms of C are used if 32.1 grams of B4C are produced? (4 points)
Answers:
1. A
2. D
3. A
4. C
5. A
6. D
7. D
8. D
9. D
10. D
11. C
12. A
13. A
14. A
15. C
16. B
17. A
18. C
19. (a) double replacement (b) Ca(NO3)2 (aq) + Na2SO4 (aq)  2 NaNO3 (aq) + CaSO4 (s)
20. (a) single replacement (b) Ni (s) + CuCl2 (aq)  Cu (s) + NiCl2 (aq)
21. (a) combustion
(b) 2 CH3OH (ℓ) + 3 O2 (g)  2 CO2 (g) + 4 H2O (ℓ)
22. (a) 2 B2O3 (s) + 7 C (s)  B4C (s) + 6 CO (g)
(b) 55.25 g/mol
(c) 0.275 mol
(d) 5.96 g B4C
(e) 2.45 × 1024 atoms C
(c) CaSO4
(c) Ni ; Cu
(c) 1.5 mol