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Coppin State CollegeDepartment of Natural Sciences
CHEM 103.101 Exam #4Dr. Alfred N. Amah
Name ______
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This examination consists of 20 multiple choice questions; carefully read each question and all the possible responses. Choose the correct answer by marking the alphabet before your choice on the scantron answer sheet. GOOD LUCK!
Multiple Choice Questions (100 points).
1. How many moles of oxygen are required to combine with 0.500 mol of hydrogen in the reaction that produces water by the following balanced equation?
a. 1.0 mol
b. 0.50 mol
c. 2.0 mol
d. 0.250 mol
2. How many moles of hydrogen gas are needed to react with oxygen to form one mole of water from the above balanced chemical equation?
a. 1.0 mol
b. 0.50 mol
c. 2.0 mol
d. 0.250 mol
3. A student was asked to prepare 12.5 g of NaCl. How many moles is this? [NaCl = 58.5 g/mol]
a.12.5 mol
b. 0.214 mol
c.2.14 mol
d. 5.85 mol
4. What will be the coefficient of O2 when the following incomplete equation is correctly balanced?
a. 2
b. 3
c. 4
d. 6.
5. What will be the coefficient of aluminum (Al) when the following incomplete equation
is correctly balanced?
a. 2
b. 3
c. 4
d. 6
6. Formaldehyde, CH2O is a toxic gas with a pungent odor. Large quantities are consumed in the manufacture of plastics, and a water solution of the compound is used to preserve biological specimen. The mass percentage of the element carbon in formaldehyde is? [ C = 12.0; H = 1.0; O = 16.0]
a. 12%
b. 30%
c. 40%
d. 60%
7. Malic acid, an organic acid found in apples, contains C, H, and O in the following ratios: C1.0H1.5O1.25. The empirical formula of malic acid is?
a. C1H2O1
b. C5H6O6
c. C4H6O5
d. C6H12O6
8. When glucose undergoes complete combustion, the products are carbon dioxide and water according to the following chemical equation:
______C6H12O6 + _____O2 ______CO2 +______H2O
When this equation is correctly balanced, the coefficient for oxygen, O2, will be?
a. 2
b. 3
c. 4
d. 6
9. Ammonia reacts with fluorine in the gaseous state to produce dinitrogen tetrafluoride and hydrogen fluoride according to the following equation:
______NH3(g) + _____F2(g) ______N2F4(g) +______HF(g)
When this equation is correctly balanced, the coefficient of fluorine, F2, will be?
a. 3
b. 4
c. 5
d. 6
10. Potassium chlorate decomposes in the presence of oxygen according to the following equation given below.
_____KClO3 + _____O2 ______KCl +. ______O2
When this equation is correctly balanced, the coefficient of the oxygen, O2, in the product of the reaction will be?
a. 2
b. 3
c. 4
d. 6
11. The coefficient of the oxygen, O2, in the reactant in the balanced equation is?
a. 1
b. 2
c. 3
d. 5
12. According to balanced chemical equation given below, if 10.0 moles of oxygen and 5.0 moles of hydrogen are mixed, the maximum moles of water that can be produced will be?
a. 1.0
b. 2.0
c. 3.0
d. 5.0
13. According to the equation below, the maximum amount of water that can be obtained given 1.0 mole of oxygen and 5.0 moles of hydrogen are mixed will be?
a. 18.0 g
b. 26.0 g
c. 36.0 g
d. 40.0 g
14. Given the unbalanced equation:
The number of moles of oxygen, O2, which will react with 1.6 mole of iron, Fe, to produce iron(III) oxide, Fe2O3, is:
a. 1.2 mol
b. 1.6 mol
c. 2.2 mol
d. 2.4 mol
15. Phosphorus trichloride may be prepared by the reaction of phosphorus with chlorine gas according to the balanced chemical equation given below:
______P4(s) + Cl2 (g)PCl3(s)
Which of the following is the correct stoichiometric coefficients to balance this equation?
a. 2, 6, 8
b. 1, 6, 4
c. 1, 3, 4
d. 3, 9, 3
16. In a balance chemical equation, what is balanced?
a.atoms
b.moles
c.molecules
d.atoms and molecules
17. Carbon disulfide, CS2, can be made from the reaction of graphite, C(s) and SO2 which also produces carbon monoxide according to the following equation:
______C(s) +_____ SO2 (g)______CS2(l) + ______CO (g)
Which of the following is the most correct set of coefficients to balance this equation?
a. 2, 1, 1, 2
b. 5, 2, 3, 2
c. 5, 2, 1, 4
d. 3, 3, 1, 2
18.The theoretical yield of iron in the process:
2Al(s) + Fe2O3(s) Al2O3(s) 2 Fe(l) was 30.0 grams.
If the actual yield of iron were 25.0 g in the process, the percent yield will be?
a.38.3%
b.83.3%
c.58.3%
d.68.3%
18. A sample of 2.00 mole of CH4 contains how many grams of methane, CH4?
a.16.0 g
b.28.0 g
c.32.0 g
d.42.0 g.
20. C3H8(g) + 5O2 (g)3CO2(g) + 4 H2O (l)
Calculate the mass of oxygen needed to react with 1.00 mole of C3H8 to form carbon dioxide and water. (O = 16.0 ; C = 12.0).
a. 80.0 g
b. 160.0g
c. 320.0 g
d. 40.0 g