Final Examination
Chemistry 121, Winter 2011
Show all your work for full credit; please turn your cell phones off.
1. [10 pts] For each of the following, identify the event described as a PHYSICAL or CHEMICAL change or property:
___a. Nitrogen dioxide decomposes into nitrogen and oxygen.
___b. Nitrogen gas is mixed with oxygen gas to produce a mixture.
___c. A mixture of ethanol and water is separated by distillation.
___d. Helium gas is inert. (That is, it does not react with other substances.)
___e. Solid carbon dioxide sublimates.
2. [8 pts] If the density of sulfuric acid is 15.28 lb/gal, what is the volume (in mL) of 4.9 g?
3. [8 pts] Convert 88 g/cm3 to mg/cL
4. [4 pts] Perform the following calculations, including the correct number of significant figures in the final answer:
a) (10461.2 x 0.0891) =
b) 13.901 + 0.01 =
5. [6 pts] Write the symbol of an element that matches each of the following descriptions. (There may be more than one
correct answer for each – just give one.)
____ a.
____ b.
____ c.
____ d.
____ e.
____ f.
A halogen in the 4th period
A transition metal in the same group as Cu
An element with four valence electrons
An element with very similar chemical properties as oxygen
A noble gas with only 2 valence electrons
An alkali metal.
6. [8 pts] How many…
…subshells in the 4th shell of an atom? ____
…electrons can occupy one orbital of the 3d subshell? ____
…orbitals in the 4p subshell? ____
…orbitals are in the 2nd shell of an atom? ____
7. [9 pts] Write the complete electron configurations of the following:
a. Ni
b. P3c. Rb+
8. [6 pts] Identify each of the following as a covalent (C) or an ionic (I) compound:
a. CuNO3
b. CH4O
c. NH4I
9. [8 pts] Each of the statements below describe either ionic (I) or covalent (C) compounds. Identify which type of
compound is described (I or C):
____ a. Substances of this type of compound tend to have very high melting points.
____ b. Compounds between two or more nonmetal elements are of this type.
____ c. This type of compound has very strong bonds.
____ d. This type of bonding occurs after atoms gain or lose electrons, to become charged.
10. [6 pts] Why does Mg tend to form an ion of +2 charge? (As opposed to forming Mg3+ or Mg2- or any other charge?)
11. [8 pts] What mass of C4H8 would contain 4.56 x 1022 molecules?
12. [6 pts] A can of shaving cream contains gas at a pressure of 1.065 atm and a temperature of 24 degrees C. If the
pressure of the gas increases to 3.000 atm, the can will explode. If you heat the can, at what temperature would it
explode?
13. [9 pts] Write a complete and balanced equation for each of the following descriptions of reactions.
a. Lithium and oxygen react to create lithium oxide.
b. Water and solid calcium react to produce hydrogen gas and aqueous calcium hydroxide.
c. Magnesium nitrate and lithium phosphate combine to form magnesium phosphate and lithium nitrate.
14. [12 pts] Write the follow reactions for the precipitation reaction which occurs between Pb(NO3)2 (aq) and AlCl3 (aq):
molecular:
ionic:
net ionic:
15. [4 pts] Suppose you are given the following four separate aqueous solutions:
Li3PO4 (aq)
Ba(NO3)2 (aq)
Ag2SO4 (aq)
NaCH3CO2 (aq)
Choose two (that is, one pair) that will form a precipitate when mixed together. Circle the two, and give the
formula of the precipitate.
16. [12 pts] Determine whether or not each of the following molecules are polar. Justify your answer thoroughly with 3D sketches:
a) OF2
b) CF3H
c) SO3
17. [6 pts] List all the intermolecular forces present in each of the following liquids:
a) OF2
b) CF3H
c) SO3
18. [6 pts] Draw a Lewis dot structure of each of the following: a) SiO32-
b) NO2-
19. [8 pts] Identify each of the following as being an electrolyte, nonelectrolyte or weak electrolyte.
a) NH4Cl (aq)
b) HI (aq)
c) HNO3 (aq)
d) Li3CO3 (aq)
20. [6 pts] Write a chemical equation to show the weak acid, HF, reacting with water. Which side of the equilibrium
would be favored?
21. [3 pts] Which of the following three solutions is the most ACIDIC?
Solution A -- [OH-] = 1.3 x 10-8 M
Solution B -- [OH-] = 8.3 x 10-7 M
Solution C -- [OH-] = 4.2 x 10-11 M
22. [6 pts] A cleaning fluid sample has a pH = 8.1. Calculate the [OH-] and [H3O+] for the sample.
23. [6 pts] Calculate the pH of 0.0040 M HBr.
24. [3 pts] Which of the following solutions would be the most basic?
a) 1.0 M NH3
b) 1.0 M HCl
c) 1.0 M HC2H3O2
25. [3 pts] Which of the following solutions would have the lowest pH?
a) 1.0 M NaOH
b) 1.0 M HNO3
c) 1.0 M HC2H3O2
26. (6 pts) What volume of a 5.0 x 10-3 M NaCl solution should you use in order to obtain 66.0 mg of the solute?
27. [10 pts] For the following exothermic reaction, determine which direction the equilibrium will shift for each
disturbance:
N2(g) + 2 O2(g)  N2O4 (g)
a) add some N2O4
b) remove some O2
c) add more N2
d) decrease the temperature
e) decrease the pressure
28. [10 pts] Calculate the pH of a solution of 0.0075 M Al(OH)3 (aq).
29. [8 pts] How would you prepare 600.0 mL of 0.44 M sodium phosphate (aq) from a solution of 1.35 M Na3PO4? Be
specific.