CHEM 1406 Practice Exam 2: Chemical Reactions and Quantities, Matter and Energy, and Gases These questions taken from the web resources made available from San Diego Miramar College, a member of the San Diego Community College District (SDCCD). Modifications have been made for clarity, to correct typos, and better align questions to TCC curriculum. We thank the faculty of San Diego Miramar College for making this resource available to us. Other sources include the test bank associated with the Chemistry 1406 Timberlake text. I. Chemical Reactions and Quantities Select the best answer to each of the following questions: 1. Predict the missing product in the following unbalanced equation. Mg + N 2 → ___ A) MgN B) Mg 3 N C) Mg 2 N D) Mg 3 N 2 E) none of the above 2. Which reaction below gives a balanced equation such that the sum of the coefficients equals 10? A) HCl(aq) + Cr(s) → CrCl 3 (s) + H 2 (g) B) FeCl 3 (s) + Na 2 CO 3 (aq) → Fe 2 (CO 3 ) 3 (aq) + NaCl(aq) C) PbS(aq) + H 2 O 2 (aq) → PbSO 4 (aq) + H 2 O (l) D) C 4 H 10 (l) + O 2 (g) → CO 2 (g) + H 2 O(l) E) none of the above 3. Which equation below violates the law of conservation of mass? A) 2CaCO 3 → 2CO 2 + 2CaCO B) 4H 2 + 2O 2 → 4H 2 O C) 2HCl + Na 2 OH → HOH + 2NaCl D) AgCl + NaNO 3 → AgCl + NaNO 3 E) all of these 4. Which reaction below gives a balanced equation such that the sum of the coefficients of the reactants equals 5? A) C 5 H 10 (l) + O 2 (g) → CO 2 (g) + H 2 O (l) B) CoCl 3 (s) + CaCO 3 (aq) → Co 2 (CO 3 ) 3 (aq) + CaCl 2 (aq) C) PbSO 4 (aq) + H 2 O(l) → PbS(aq) + H 2 O 2 (aq) D) HBr(aq) + Cr(s) → CrBr 3 (s) + H 2 (g) E) none of the above 5. In a combustion reaction, which of the following is not a product? A) oxygen B) water C) carbon dioxide D) energy E) all of these are products of a combustion reaction.
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CHEM 1406 Practice Exam 2:
Chemical Reactions and Quantities, Matter and Energy, and Gases These questions taken from the web resources made available from San Diego Miramar College, a member of the San Diego
Community College District (SDCCD). Modifications have been made for clarity, to correct typos, and better align questions to TCC
curriculum. We thank the faculty of San Diego Miramar College for making this resource available to us. Other sources include the
test bank associated with the Chemistry 1406 Timberlake text.
I. Chemical Reactions and Quantities
Select the best answer to each of the following questions:
1. Predict the missing product in the following unbalanced equation. Mg + N2 → ___
A) MgN
B) Mg3N
C) Mg2N
D) Mg3N2
E) none of the above
2. Which reaction below gives a balanced equation such that the sum of the coefficients equals 10?
A) HCl(aq) + Cr(s) → CrCl3(s) + H2(g)
B) FeCl3(s) + Na2CO3(aq) → Fe2(CO3)3(aq) + NaCl(aq)
C) PbS(aq) + H2O2(aq) → PbSO4(aq) + H2O (l)
D) C4H10(l) + O2(g) → CO2(g) + H2O(l)
E) none of the above
3. Which equation below violates the law of conservation of mass?
A) 2CaCO3 → 2CO2 + 2CaCO
B) 4H2 + 2O2 → 4H2O
C) 2HCl + Na2OH → HOH + 2NaCl
D) AgCl + NaNO3 → AgCl + NaNO3
E) all of these
4. Which reaction below gives a balanced equation such that the sum of the coefficients of the reactants
equals 5?
A) C5H10(l) + O2(g) → CO2 (g) + H2O (l)
B) CoCl3(s) + CaCO3 (aq) → Co2(CO3)3(aq) + CaCl2(aq)
C) PbSO4(aq) + H2O(l) → PbS(aq) + H2O2(aq)
D) HBr(aq) + Cr(s) → CrBr3(s) + H2(g)
E) none of the above
5. In a combustion reaction, which of the following is not a product?
A) oxygen
B) water
C) carbon dioxide
D) energy
E) all of these are products of a combustion reaction.
6. What is the sum of the coefficients on H2O and H3PO3 in the following equation when balanced?
__PCl3 + __H2O → __H3PO3 + __HCl
A) 2
B) 3
C) 4
D) 6
E) none of the above
7. What is the sum of the coefficients on Fe2S3 and HCl in the following equation when balanced?
__FeCl3 + __H2S → __Fe2S3 + __HCl
A) 23
B) 5
C) 6
D) 7
E) none of the above
8. What is the sum of all the coefficients after the following equation is balanced?
__CO2 + __H2O → __C6H12O6 + __O2
A) 4
B) 24
C) 18
D) 19
E) none of the above
9. Which of the following gives the balanced equation for this reaction?
__K3PO4 + __Ca(NO3)2 → __Ca3(PO4)2 + __KNO3
A) KPO4 + CaNO3 + KNO3
B) K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + 3KNO3
C) 2K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + 6KNO3
D) 2K3PO4 + 3Ca(NO3)2 → Ca3(PO4)2 + 6KNO3
E) K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + KNO3
10. What is the sum of the coefficients when the following equation is balanced?
__ FeCl3 + __ AgNO3 → __ Fe(NO3)3 + __ AgCl
A) 3
B) 4
C) 6
D) 8
E) none of the above
11. The following reaction takes place when an electric current is passed through water. It is an
example of a __________ reaction.
2 H2O → 2H2 + O2
A) combination
B) single replacement
C) dehydration
D) decomposition
E) double replacement
12. Which of the following is an oxidation-reduction reaction?
A) CaCl2 + Na2SO4 → CaSO4 + 2NaCl
B) KOH + HNO3 → H2O + KNO3
C) N2 + O2 → 2NO
D) AgNO3 + NaCl → AgCl + NaNO3
E) Al2(SO4)3 + 6KOH → 2 Al(OH)3 + 3K2SO4
13. What is oxidized and what is reduced in the following reaction?
2Al(s) + 3Br2 (g) → 2AlBr3(s)
A) Al is oxidized and Br2 is reduced.
B) AlBr3 is reduced and Br2 is oxidized.
C) Al is reduced and Br2 is oxidized.
D) AlBr3 is reduced and Al is oxidized.
E) AlBr3 is oxidized and Al is reduced.
14. Which of the following describes an oxidation reaction?
A) loss of electrons or loss of oxygen
B) loss of electrons or gain of oxygen
C) loss of electrons or gain of hydrogen
D) gain of electrons or gain of oxygen
E) gain of electrons or loss of H
15. What is the formula weight of beryllium sulfate?
A) 41.0
B) 57.0
C) 105.0
D) 106.8
E) none of the above
16. Avogadro's number is the number of
A) particles in 1 mole of a substance.
B) amu in 1 mole of a substance.
C) grams in 1 mole of a substance.
D) moles in 6.02 × 1023
grams of an element.
E) moles in 6.02 × 1023
amu of an element.
17. One mole of helium gas weighs
A) 1.00 g.
B) 2.00 g.
C) 3.00 g.
D) 4.00 g.
E) 8.00 g.
18. What is the molar mass of Mg3(PO4)2, a substance formerly used in medicine as an
antacid?
A) 71.3 g
B) 118.3 g
C) 150.3 g
D) 214.3 g
E) 262.9 g
19. Which amount has the smallest mass?
A) 1.25 mol Na
B) 0.236 mol Mg
C) 0.11 mol Ba
D) 3.75•1022
atoms Se
E) all of the above have the same mass.
20. What is the mass of a thimble of water which contains 4.0•1021
molecules?
A) 1.2 g
B) 1.2•10-8
g
C) 12 g
D) 0.12 g
E) none of the above
21. State the mass of oxygen atoms (grams) in one mole of C7H5NO3S (saccharin):
A) 16 g
B) 48 g
C) 183.0 g
D) 32 g
E) none of the above
22. The compound MgSO4 is called Epsom salt. What mass is needed to prepare a bath with 5.000 mole of
Epsom salt?
A) 0.04156g
B) 24.06g
C) 120.3g
D) 601.5 g
E) none of the above
23. How many molecules of TNT, C7H5N3O6 (Mol. Wt. = 227.0 g/mol ) are in 5.8 moles of TNT?
A) 3.5•1024
B) 21
C) 1.3•103
D) 121
E) none of the above
24. Calculate the number of moles of aspirin, C9H8O4, in a 8.0 g tablet.
A) 4.4•10-2
mol
B) 4.6•10-3
mol
C) 4.9 mol
D) 0.022 mol
E) none of the above
25. A typical cholesterol deposit in an artery might have a mass of 3.9 mg of cholesterol (C27H46O). How
many molecules of cholesterol are in this mass?
A) 1.01•10-2
B) 1.01•10-5
C) 6.1•1018
D) 6.1•1021
E) none of the above
26. Which chemical has a molar mass of 180 g/mol?
A) KI
B) NH3
C) C2Cl6
D) C6H12O6
E) none of the above
27. How many grams of N2 will be required to completely react with 9.3 g of H2 in the reaction:
N2 + 3H2 → 2NH3
A) 1.3•102
B) 2.0
C) 43
D) 3.9•102
E) none of the above
28. How many moles of Al are needed to react with 2.5 mol of Fe2O3 in the equation:
2Al + Fe2O3 → Al2O3 + 2Fe
A) 135
B) 2.0
C) 5.0
D) 1.25
E) no answer
29. The number of grams of K2O produced from the oxidation of 4.0 grams of K in the reaction:
K(s) + O2 (g) → K2O (g) (Unbalanced)
A) 4.8 g
B) 4.0 g
C) 9.4 g
D) 6.3 g
E) none of the above
30. Tungsten W, is produced from tungsten(VI) oxide according to the following unbalanced equation:
__WO3(s) + __H2(g) → __W(s) + __H2O(l).
How many grams of tungsten metal could you produce from 36.0 g of tungsten(VI) oxide?