CHEM 1405 Practice Comprehensive Final Exam and Answer Keys.
Corwin’s Introductory Chemistry
PART I – Multiple choice (3 points each).
Do NOT mark on the test. Write your name and answers in Scantron.
1. Round off the following measurement to the four significant digits: 107.300 g
A) 107 g
B) 107.0 g
C) 107.3 g
D) 107.5 g
2. Add 7.7 g to 51.65 g and round off the sum to the proper significant digits
A) 59.0 g
B) 59.4 g
C) 59.43 g
D) 59.44 g
3. Express 0.000000000010 as an exponential number.
A) 1.0 X 10–10
B) 1.0 X 10–12
C) 1.0 X 10–11
D) 1.0 X 1012
4. Which of the following unit factors is derived from: 1 foot = 12 inches?
A) 12 feet/ 12 inches B) 12 inches/ 12 feet C) 1 foot/ 12 inches D) 1760 yard/ 1 mile
5. The radius of a tin atom is 1.41 X 10–8 cm. What is the radius in meters? Given 1m = 102 cm
A) 1.41 X 10–16m
B) 1.41 X 10–10m
C) 1.41 X 10–4m
D) 1.41 X 10–1m
6. A glass cylinder contains four separate liquid layers: chloroform (d = 1.49 g/mL), acetic acid (d
= 1.05 g/mL), ether (d = 0.708 g/mL). If a stone (d = 1.30 g/mL) is added to the cylinder, where
does it come to rest?
A) On bottom of the chloroform layer
B) On top of chloroform layer
C) On top of acetic acid layer
D) On the top of ether layer
7. How much energy is released when a 50.0 g sample of solid aluminum was cooled from
100.0°C to 60.0°C. The specific heat of the metal is 0.210 cal/(g°C).
A) 168.0 calories
B) 210.0 calories
C) 840.0 calories
D) 420.0 calories
8. What is the equivalent temperature, in Kelvin, for –103°C?
A) –367 K
B) –179 K
C) –94 K
D) 170 K
9. Which of the following elements is an example of a semimetal?
A) He
B) Ca
C) Cr
D) Si
10. Use the periodic table and predict which of the following elements a liquid at 25°C.
A) Bi
B) S
C) Hg
D) Ar
11. How many neutrons are in the nucleus of one atom of sulfur–31?
A) 15
B) 16
C) 18
D) 31
12. What is the maximum number of electrons that can occupy a 3p sublevel?
A) 2
B) 6
C) 10
D) 14
13. What is the electron configuration for a copper (I) ion, Cu+ ?
A) [Ar]
B) [Ar] 4s2 3d9
C) [Ar] 4s1 3d10
D) [Ar] 4s0 3d10
14. NO2 is classified as which of the following?
A) Binary ionic
B) Ternary ionic
C) Binary molecular D) Ternary molecular
15. What is the formula for the ionic compound composed of calcium ion, Ca2+ and OH– ?
A) CaOH
B) CaOH3
C) Ca3OH
D) Ca(OH)2
16. What are the products from the following decomposition reaction?
CaCO3 (s) →
A) Ca and CO2 B) CaO and CO2
C) Ca2O3 and CO2
D) CaO, H2O, and CO2
17. How many carbon dioxide molecules, CO2, have a mass of 22.0 g?
A) 1.20 X 1023 molecules
B) 1.20 X 1024molecules
–24
C) 1.93 X 10 molecules
D) 3.01 X 1023 molecules
18. If 0.5 mol of krypton gas exerts a pressure of 1.00 atm at 100°C, what is the volume of the
gas? (R = 0.08206 L atm./ mol K)
A) 7.6 L
B) 10.2 L
C) 15.3 L
D) 30.6 L
19. How many valence electrons are in an oxygen atom and an oxide ion?
A) 1 and 6, respectively
B) 2 and 8, respectively
C) 6 and 8, respectively
D) 6 and 10, respectively.
20. Which of the following ions does not have the following electron configuration?
1s2 2s2 2p6 3s2 3p6?
A) Cl–
B) S2–
C) K+
D) Sr2+
21. Given the electronegativity values H = 2.1, N = 3.0, O = 3.5, P = 2.1, and Cl = 3.0.
Which of the following molecules contains polar covalent bonds?
A) O2
B) HCl
C) PH3
D) N-Cl bond
22. Which molecule contains hydrogen bond?
A) CO2
B) NaCl
C) HF
D) H2
23. What are the products from the complete combustion of a hydrocarbon?
A) Carbon dioxide and water
B) Carbon monoxide and hydrogen
C) Carbon monoxide and water
D) Carbon dioxide and hydrogen
24. What is the systematic name for for MgSO4•7H2O ?
A) Magnesium (II) sulfite heptahydrate
B) Magnesium sulfite heptahydrate
C) Magnesium (II) sulfate heptahydrate
D) Magnesium sulfate heptahydrate
25. What is the strongest intermolecular force that occurs between Br2 molecules?
A) Dipole forces
B) Dispersion forces C) Hydrogen bonding D) Ionic bonding
PART II – Show your work: 25 points total: 5 points each.
Name: ___________________________________________
1. Perform the following metric-metric conversions:
a) 125 cm to mm, given 1 cm = 10 mm.
Answer: 1250 mm
b) 255 mg to μg , given 1 mg = 1000 μg.
Answer: 255000 μg
2. A sample of fluorine gas occupies 650 mL at 720 mmHg and 100°C. What is the mass
of the sample? Given 1 atm = 760 mmHg; 1 L = 1000 mL; K = °C + 273
Answer (a) PV = nRT (720/760)x(650/1000) = nx0.082x(100+273) n=0.020 mole
m=0.020x(19x2) = 0.765 g
3. Calculate the heat required to convert 10.0 g of water from 20.0°C to 90.0°C.
The specific heat of water is 1.00 cal/(g°C).
Answer q = 10.0x1.00x(90-20) = 700 joules
4. If 10 moles of butane are combusted according to the following reaction,
2 C4H10 (g) + 13 O2 (g) → 8 CO2 (g) + 10 H2O (g)
how many moles of water will be formed?
Answer: 10 moles C4H10 (g) x
10 moles H2O (g)
2 moles C4H10 (g)
=
10x10
2
= 50 moles H2O (g)
5. Dioxane, a common solvent for plastics, is 54.5 % C, 9.15 % H, and 36.3 % O by mass. What is
the empirical formula of dioxane?
Answer: Mole C : mole H: mole O = 54.5/12 : 9.15/1.008 : 36.3/16 = 4.54 : 9.15 : 2.27 =
4.54/2.27 : 9.15/2.27 : 2.27/2.27 = 2 : 4 : 1 Thus, the empirical formula is C2H4O.