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CHEMISTRY 1301. SECTION 2. L1–4, L5–6
Fall 1997
Dr. Roberto Ma. S. Gregorius
Name __________________________
I.
Information Retrieval. 10 Questions, 3 points each, 30 points. Mark answers on
a Scantron. (Try not to spend more than 15 minutes here.)
1.
The name of the compound with a molecular formula of Zn(MnO4)2 is:
(a) zinc permanganate
(b) zinc (II) permanganate
(c) zinc (II) dimanganese oxide
(d) zinc (II) monomanganesetetroxide
2.
The molecular formula for the compound which has the chemical name of nickel
(III) dichromate is:
(a) NiCr2
(b) NiCr2O7
(c) Ni2(Cr2O7)3
(d) Ni2Cr3
3.
The compound dinitrogen tetroxide contains:
(a)
(b)
(c)
(d)
4.
0.5 moles of a particular molecule is equivalent to
(a)
(b)
(c)
(d)
5.
1 N and 3 O
2 N and 3 O
2 N and 4 O
3 N and 4 O
6.022 x 1023 of that molecule
the number of grams of a substance equal to its molar mass
3.0 x 1023 of that molecule
6 g of carbon
The molar mass of phosphorous is:
(a) 30.97 g/mol
(b) 39.10 g/mol
(c) 195.09 g/mol
(d) ~210 g/mol
6.
The molecular weight of Mg(OH)2 is:
(a) 41 g/mol
(b) 58 g/mol
(c) 83 g/mol
(d) 106 g/mol
7.
6.0 g of nitrogen atoms should contain
(a)
(b)
(c)
(d)
8.
1.41 x 1023 atoms
7.12 x 1023 atoms
6.02 x 1023 atoms
2.58 x 1023 atoms
The balanced chemical equation for the following combustion reaction is:
™
C3H7OH(l) + O2(g)
(a) C3H7OH(l) + O2(g)
™
CO2(g) + H2O
CO2(g) + H2O
(b) C3H7OH(l) + 7O2(g)
™
3CO2(g) + 8H2O
(c) C3H7OH(l) + 5O2(g)
™
3CO2(g) + 4H2O
(d) none of the above
9.
In the following unbalanced equation,
Na2CO3(aq) + HCl(aq)
™
NaCl(aq) + H2O(l) + CO2(g)
when the reaction is balanced, the sum of all the coefficients add up to:
(a)
(b)
(c)
(d)
4
5
6
7
10. Which of the following statements is false?
(a)
(b)
(c)
(d)
If there is a limiting reagent, there is also a substance in excess.
The limiting reagent controls the reaction.
If the limiting reagent is a gas, then it does not control the reaction.
The mass of all the products depend on the mass of the limiting reagent.
II. Analysis. 5 questions, 10 points per question. Note your answers on your
Scantron. Try to save at least 15 minutes for part III.
11. In the balanced reaction given below:
Mg(s) + 2HCl(aq)
™
MgCl2(aq) + H2(g)
If 3.45 g of HCl were to react with an excess amount of Mg, the amount of
hydrogen gas produced is:
(a) 0.0954 g
(b) 0.287 g
(c) 0.143 g
(d) 0.573 g
12. In the decomposition of phosphorous pentachloride, phosphorous solid and
chlorine gas are created.
If 2.50 g of phosphorous were decomposed, how many grams of chlorine gas
would be produced?
(a) 0.851 g
(b) 1.06 g
(c) 2.13 g
(d) 2.50 g
13. In the reaction of iron with nitric acid to form iron (II) nitrate and hydrogen gas
(H2), if 1 mole of iron were to be reacted with 1 mole of nitric acid, how many
moles of iron (II) nitrate would form?
(a) 0.5 mole
(b) 1 mole
(c) 1.5 mole
(d) 2 mole
14. 2.55 g of sulfuric acid (an acid) is reacted with 1.88 g of sodium hydroxide (a
base). The reaction takes place as a solution in water. After the reaction is
completed the acidity or basicity of the solution is tested. Which of the following
statements is true?
(a) The solution was found to be acidic.
(b) The solution was found to be basic.
(c) The solution was found to be neither acidic nor basic, it was neutral.
(d) The problem does not have enough information to determine if the solution
was found to be acidic, basic or neutral.
15. Which of the following would have the most number of total atoms?
(a) 1mol of hydrogen gas
(b) 20g of ammonia
(c) a mole of copper atoms
(d) 15g of methane (CH4)
III. Show your thinking process. Answer the question as concisely as possible in the space
provided. (1 question, 20 points)
16. A teaspoon holds 2.00 mL of pure water at 27.0˚C. A student pours out the water at
a rate of 1,000 molecules per second. Could the student pour out all the water while
holding his/her breath? Could the student pour out all the water in a day? If the
student does nothing since birth except pour out the water at that rate, would the
student be finished by the time s/he dies of old age at 90? Would it take longer than
that? Show your calculations.