CHEM 1411 Practice Exam #1
(Ch. 1-4)
Name:
Score
Part I. Multiple choice questions. ( 2 points each)
Direction- Please write your correct choice in space provide.
____1. The distance between carbon atoms in ethylene is 134 picometers. Which of the
following express the distance in meters?
A. 1.34x10-13 m
B. 1.34x10-10 m
C. 1.34x10-7 m
D. 1.34x10-6 m
____ 2. Acetic acid boils at 244.2 0F. What is boiling point in degrees celsius?
A. 167.7 0C
B. 153.4 0C
C. 117.8 0C
D. 103.7 0C
____ 3. Which of the following expressed measurement 52,030.2 m in correct scientific
notation?
A. 5.20302x104 m
B. 5.203x104 m
C. 5.20x104 m
D. 5.2x104 m
____ 4. Select the answer with correct number of decimal places for the following sum.
4.65 g + 2.0 g + 19.6442 g =
A. 26.2942 g
B. 26.29 g
C. 26 g
D. 26.3 g
____ 5. Which of the following is a non-metal?
A. Li
B. Be
C. Os
D. I
____ 6. Bromine is the only non-metal that is liquid at room temperature. Consider the
isotope bromine-81, 3581 Br. Select the combination which list the correct atomic
number, neutron number , and mass number respectively.
A. 35,46,81
B. 35,81,46
C. 81,46,35
D. 46,81,35
____ 7. Which of the following name is correct for given chemical formula?
A. I2O5 , iodine pentoxide
C. PbO , lead(I) oxide
B. LiNO3 , lithium nitrate
D. H2SO4 , hydrosulfuric acid
____ 8. Which of the following chemical formula is not correct for given chemical name?
A. ferric oxide , Fe2O3
C. tetrasulfur dinitride , S4N2
B. calcium hydroxide , Ca(OH)2
D. potassium chlorite , KClO3
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------9. What is the coefficient on H2O when the following equation is correctly balanced
NH4NO2 ----> N2 + H2O
A. 1
B. 2
C. 3
D. 5
-----10. Which one of the following reactions is not balanced?
A. 2C6H6(l) + 15O2(g)  12CO2(g) + 6H2O(g)
B. B2O3(s) + 6HF(l)  2BF3(g) + 3H2O(l)
C. UO2(g) + 4HF(l)
 UF4(s) + 4H2O(l)
D. 2B5H9(l) + 12O2(g)  5B2O3(s) + 9 H2O(g)
____11. Which identification is INCORRECT for the element?
A. Na, sodium
B. S, sulfur
C. P, potassium
D. Zn, zinc
____12. Which of the following is not a chemical change?
A. burning coal
C. boiling an egg
B. making bread rise using baking soda
D. boiling water
____13. Which of the following is improperly labeled?
A. Cu- transition metal
C. Br- halogen
B. Mg- alkaline earth metal
D. U- noble gas
____14. How many carbon atoms are in 200 molecules of CH3-CH2-COO-CH3
A. 800
B. 200
C. 600
D. 400
------15. A temperature of 63 ˚F is ---------------- K
A. 17
B. 276
C. 290
D. 29
( hint: C = K-273, F=9/5C + 32)
-------16. Which species has 45 neutrons?
A. 36Kr80 B. 35Br80 C. 34Se78 D. 17Cl34
-------17. Identify the atom which has mass number 17, proton number 8, neutron number 9,
electron number 10
A.
35
17Cl
(-1 charge) B. 8O17 (-2 charge) C. 8O18 (-2 charge) 4. non of the above
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------18. Isotopes are atoms of the same elements that have the same number of ____________
but different number of ______________________.
A. protons, electrons
B. neutrons, protons
C. protons, neutrons
D. electrons, protons
-------19. One formula unit of calcium carbonate (CaCO3) has a mass of 100g. Which of
the following quantities of compounds has an equal number of formula units?
A. 62 g of NaCl
B. 56 g of MgCl2
C. 142 g of P2O5
D. 45 g of NaOH
-------20. Avogadro’s number is
A. Atomic mass number in grams
B. Number of fundamental units in a mole of
substance
C. Total atomic number of a formula unit D. Non of the above
-------21. The number of atoms of lithium (atomic mass unit 6.94) in 4.3 moles is
A. 4.179x1024
B. 29.84
C. 1.61
D. 2.589x1024
-------22. How many grams of Ibuprofen (C13H18O2) are present in a bottle that contains
4.97x1019 molecules of this compound?
A. 0.0170 g
B. 17 g
C. 1.70 g
D. 170 g
-------23. How many atoms of carbon are present in 10.0 g of table sugar (C 12H22O11)
A. 10x1023 atoms
B. 2.11x1023 atoms
C. 342x1023 atoms
D. 3420 atoms
-------24. How many grams of CuO are needed to produce 150 g of copper?
A. 300 g
B. 266 g
C. 235 g
D. 188
-------25. If the empirical formula of a compound is CH2, but the weight of 1 mole of the
compound is 140 g, what is its molecular formula?
A. C14H28
B. C10H20
C. C8H16
D. C6H12
------26. Which of the following compound is not a strong acid?
A. HCl
B. H2SO4
D. HSO4-
C. HNO3
------27. Molecules that undergo complete dissociation to form H3O+ in water are called
A. Weak acid
B. Strong Base
C. Strong acid
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D. Weak Base
------28. Which of the following is an acidic salt
A. Na2SO4
B. NaHSO4
C. H2SO4
D. Na3PO4
------29. A 1-liter solution of 2 M NaOH can be prepared with
A. 20 g of NaOH
B. 40 g of NaOH
C. 60 g of NaOH
D. 80 g of NaOH
------30. How many grams of hydrochloric acid are in 500.0 ml of a 5.00 M solution?
A. 36.5 g
B. 182.5 g
C. 91.25 g
D. 100 g
------31. The molarity of chloride ion, Cl-(aq), in 100.0mL of 0.500 M barium chloride, BaCl2,
solution is:
A. 0.5 M
B. 0.250 M
C. 0.500 M
D. 1.00 M
------32. What amount of water must be evaporated from 0.5 L of 1 M NaOH to make it 5 M?
A. 0.1 L
B. 0.2 L
C. 0.3 L
D. 0.4 L
-------33. What is the oxidation number of Cl in ClO2− ion
A. −1
B. −3
C. + 3
D. −2
------34. Iron forms a magnetic oxide with the formula Fe3O4 that contains both Fe2+ and Fe3+ ions.
What is the average oxidation number of iron in this oxide?
A. −3
B. + 5/2
C. −5
D. +8/3
-------35. In the following reaction which element is an oxidizing agent?
KCl + 3HNO3  KClO3 + 3HNO2
A. Cl
B. N
C. O
D. K
Part II. Show all your work for complete credit.( 5 points each)
1. The density of mercury, the only metal to exist as liquid at room temperature, is 13.6 g/cm3.What is
the density in pounds per cubic inch (lb/in3) ? ( 1 lb=454 g , 1 in =2.54 cm)
2. The speed needed to escape the pull of earth,s gravity is 11.3 km/s. What is this speed in mi/hr?
( 1 mi=1.6094 km)
3. Lithium , is used in dry cells and storage batteries and in high temperature lubricants, it
has two naturally occurring isotopes, 6Li and 7Li. Calculate the average atomic mass of lithium.
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isotopes
isotopic mass(amu)
abundance(%)
6
Li
6.01521
7.50
7
Li
7.016003
92.50
4. Vitamin E contains 80.11% carbon, 11.73% hydrogen, and 7.43% oxygen. What is the
empirical formula?
5. Write the balanced equation for the combustion of butane(C 4H10) (hint: in combustion reactions
hydrocarbons are burnt completely in oxygen to form carbon dioxide, water and heat)
6. Balance the following equation by the ion-electron method
Al(s) + Cu2+(aq)→ Al3+(aq) + Cu(s)
Bonus question( 10 points)- show all your work.
1. Balance the following equation:
PCl5 + H2O ------------- H3PO4 + HCl
In one experiment, 0.360 mol of PCl5 was slowly added to 2.88 mol of water
(a). Which reactant, if either, was limiting reactant?
(b). How many moles of HCl were formed in the reaction.
CHEM 1411 SAMPLE EXAM # 1 - KEY (Ch. 1-4)
PART-I
1-B
(pico = 10 -12 , 134 x 10 -12 m = 1.34 x 10 -10 m)
2-C
C = 5/ 9(F-32) = 5/ 9(244.2 - 32) = 5/ 9(212.2) = 117.9 oC
3-A
4-D, sum = 26.2942 g , round off to the least number of decimal point (one), sum = 26.3 g
5-D; 6-A; 7-B, LiNO3 is Lithium nitrate; 8-D, potassium chlorate, KClO3
9-B; 10-C, 2H2O(l) 11-C, P is the symbol for phosphorous
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12-D, boiling water is a phase change from liquid to vapor
13-D, Uranium is an inner transition metal
14-A; 15-C; 16-B;17-B; 18-C; 19-C; 20-B; 21-D; 22-A; 23-B; 24-D; 25-B
26-D; 27-C; 28-B; 29-D; 30-C; 31-D; 32-D;
33-C
ClO2x + (2 x -2) = -1
x-4 = -1
x = 4-1
x = +3
34-D
Fe3O4
3x + (4 x -2) = 0
3x + (-8) = 0
3x – 8 = 0
3x = +8
x = +8/3
35-B
Oxidation
+1 -1
n
+1 +5 -6
+1 +5 -6
+1 +3 -4
KCl + 3HNO3 → KClO3 + 3HNO2
Reduction
Cl has been oxidized
N has been reduced
Therefore N is the oxidizing agent
PART-II
1.
13.6
----------- x
cm3
1 lb
-----------454 g
x
(2.54 cm)3
------------------ = 0.491 lb/ in3
1 in3
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2.
11.3 km
1 mi
3600 sec
------------- x ---------------- x ---------------- = 2.53 x 104 mi/hr
sec
1.6094 km
1 hr
3. Ave. atomic wt. of Li = (7.50/100) (6.01521) + (92.50/100) (7.016003) = 6.95 a.m.u.
4. C29H51O2
5. C4H10 + O2  CO2 + H2O
C4H10 + 6.5 O2  4 CO2 + 5H2O x 2
2 C4H10 + 13 O2  8 CO2 + 10 H2O
6. Al  Al3+ +3e oxidation half
Cu2+ + 2e  Cu Reduction half
2 (Al  Al3+ +3e) Balence
3(Cu2+ + 2e  Cu)
2Al + 3Cu2+ +6e  2Al3+ + 3Cu + 6e
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