Zumdahl Chaps 5-8
100 pts, 5 pages
2/12/16
Chemistry 111- Exam II, Spring 2005
NAME_______________________________
1. Aqueous calcium chloride and aqueous magnesium sulfate are combined in a beaker. Write the complete ionic
equation for the reaction that occurs. (12 pts)
CaCl2(aq) + MgSO4(aq) → CaSO4(s) + MgCl2(aq) CaSO4 is insoluble according to the solubility table. This is the
molecular equation, for the complete ionic we need to show the individual ions, solid still shown as solid.
Ca2+(aq) + 2Cl-(aq) + Mg2+(aq) + SO42-(aq) → CaSO4(s) + Mg2+(aq) + 2Cl-(aq) ANSWER
2. Nicotine is a natural product found in tobacco leaves. It can act as a stimulant or a depressant. It is 74.03% C,
8.70% H, and 17.27% N. Its molecular weight is 162.24 g/mol. (18 pts)
a. What is the empirical formula of nicotine? Change % to grams, convert to moles, divide by smallest
C 74.03 g/(12.011 g/mol) = 6.16 mol; 6.16/1.233 = 5
H 8.70 g/(1.008 g/mol) = 8.63 mol; 8.63/1.233 = 7
N 17.27 g/(14.01 g/mol) = 1.233 mol; 1.233/1.233 = 1
C5H7N ANSWER
b. What is the molecular formula of nicotine?
Take the molar mass (given as 162.24 g/mol) and divide by the molar mass calculated using the empirical formula.
Empirical formula mm = (5 x 12.011) + (7 x 1.008) + (1 x 14.01) = 81.12 g/mol
162.24/81.12 = 2 so multiply subscripts of empirical formula by 2
C10H14N2 ANSWER
c. A cigarette may contain up to 20.0 mg of nicotine; how many moles is that?
20 mg x 1 g/1000 mg x 1 mol/162.24 g = 1.23 x 10-4 mol ANSWER
3.
Write the formula for each of the following (16 pts):
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Zumdahl Chaps 5-8
100 pts, 5 pages
beryllium nitrate
____Be(NO3)2____
calcium fluoride
___CaF2_________
sodium sulfate
_____Na2SO4_____
iron(III)nitrate
____Fe(NO3)3____
sulfuric acid
____H2SO4_______
lithium carbonate
____Li2CO3______
potassium perchlorate
____KClO4_______
aluminum phosphate
____AlPO4_______
2/12/16
Multiple choice, circle the letter of the best answer: (3 points each):
4. Which best defines the term “empirical formula”?
a.
b.
c.
d.
e.
The formula with the smallest whole number subscripts
The experimentally determined formula
The formula of an ionic compound
The formula of the molecule itself
The formula that gives the correct molar mass
5. Based on the periodic table, which is a correct symbol for the ion formed by selenium (#34)?
a. Se2+
b. Se+
c. Se2d. See. none of the above
6.
What is the formula weight (molar mass)of ammonium sulfate?
a. 32 amu
b. 132 amu
c. 114 amu
d. 124 amu
e. none of the above
7. How many electrons are transferred to (or lost from) each iron atom in the following reaction?
4FeO(s) + O2(g)  2Fe2O3(s)
a. 0
b. 1
c. 2
d. 3
e. 4
8. Classify the following reaction.
CuCl2(aq) + AgNO3(aq)  Cu(NO3)2(aq) + AgCl(s)
a. Oxidation/reduction
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Zumdahl Chaps 5-8
b.
c.
d.
e.
100 pts, 5 pages
2/12/16
Precipitation
Decomposition
Synthesis
More than one answer is correct
9. Which is not associated with strong acids?
a. Produce H+(aq) when dissolved in water
b. Produce H2O when reacted with strong bases
c. Produce salt (i.e., an ionic compound) when reacted with strong bases
d. Produce gas when reacted with strong bases
e. HNO3(aq) and HCl(aq) are examples
10. How many grams of sodium are present in 50.7 moles of sodium?
a. 23.0 grams
b. 1166 grams
c. 1620 grams
d. 2.21 grams
e. 1.58 grams
11. How many moles of sugar (C6H12O6) are found in 463.5 g of pure sugar?
a. 2.573 moles sugar
b. 0.3887 moles sugar
c. 15.97 moles sugar
d. 8.783 moles sugar
e. 0.1138 moles sugar
12. Which is false about the following reaction?
Mg(s) + O2(g) → MgO(s)
a. it is not balanced
b. magnesium is reduced and oxygen is oxidized
c. it is a redox reaction
d. magnesium is oxidized and oxygen is reduced
e. it is a synthesis
f. more than one of the above is false
13. When a precipitation reaction occurs, the spectator ions _______.
a. Evaporate
b Are removed from the solution
c. Form a second insoluble compound in solution
d. Are left dissolved in solution
e. Disappear
14. A sample of a new compound was analyzed and found to contain 0.2322 g of carbon, .05848 g of hydrogen,
and 0.3091g of oxygen. What is the empirical formula?
a. C3H6O2
b. C2H6O2
c. C2H3O2
d. CH2O
e. CH3O
15. Predict the precipitate formed (if any) when KCl(aq) reacts with FeSO4(aq).
a. Potassium sulfate
b. Potassium chloride
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Zumdahl Chaps 5-8
100 pts, 5 pages
2/12/16
c. Iron (II) sulfate
d. Iron (II) chloride
e. No precipitate formed
16. Predict the precipitate formed (if any) when aqueous ammonium sulfide reacts with aqueous silver nitrate.
a. AgS
b. AgNO3
c. NH4NO3
d. NH4S
e. No precipitate
17. What is the balanced net ionic equation for the reaction of aqueous sodium hydroxide with aqueous iron (III)
chloride?
a. Na+(aq) + OH-(aq)  NaOH(s)
b. Na+(aq) + Cl-(aq)  NaCl(s)
c. Fe3+(aq) + 3OH-(aq)  Fe(OH)3(s)
d. Fe3+(aq) + 3Cl-(aq)  FeCl3(s)
e. There is no net reaction (i.e., no precipitate formed)
18. Which is an incorrect equivalence statement?
a. 1 mol hydrogen atoms = 6.022 X 1023 hydrogen atoms
b. 1 hydrogen atom = 1.0079 amu hydrogen
c. 6.022 X 1023 amu hydrogen = 1.0079 grams hydrogen
d. 1 mol hydrogen atoms = 1.0079 grams hydrogen
e. 1 amu = 1.66 X 10-24 g
19. How many moles of carbon are found in 24.02 grams of carbon?
a. 0.500 moles
b. 1.00 moles
c. 0.250 moles
d. 2.00 moles
e. 1.75 moles
20. The composition of carbon dioxide is:
a. 27.3% C, 72.7% O
b. 42.9% C, 57.1% O
c. 33.3% C, 66.7% O
d. 50.0% C, 50.0% O
e. 72.7 % C, 27.3% O
21. Which pair would react to form water.
a.
b.
c.
d.
e.
CH4(g) and O(g)
H2SO4(aq) and H2O(l)
KOH(aq) and NaOH(aq)
H2SO4(aq) and HNO3(aq)
HClO4(aq) and KOH(aq)
Extra Credit: (7 pts maximum) The Boston Beer Co., produced 7.00 x 105 barrels (bbl) of beer
in one year. If 1 bbl = 52 sixpacks, and production was continuous around the clock, how many
sixpacks per second were produced ?
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Zumdahl Chaps 5-8
100 pts, 5 pages
2/12/16
7.00x105 bbl/yr x 52 sixpk/bbl x 1 yr/365 d x 1 d/24hr x 1 hr/3600 s = 1.15 sixpk/s
Table 7.1 General Rules for Solubility of Ionic Compounds (Salts) in Water at 25˚C
Most nitrate (NO3-) salts are soluble.
Most salts of Na+, K+, and NH4+ are soluble.
Most chloride salts are soluble. Notable exceptions are AgCl, PbCl2, and Hg2Cl2.
Most sulfate salts are soluble. Notable exceptions are BaSO4, PbSO4, and CaSO4.
Most hydroxide compounds are only slightly soluble.* The important exceptions are NaOH and KOH. Ba(OH) 2 and
Ca(OH) 2 are only moderately soluble.
6. Most sulfide (S2-), Carbonate (CO32-), and phosphate (PO43-) salts are only slightly soluble.*
*The terms insoluble and slightly soluble really mean the same thing: such a tiny amount dissolves that it is not possible to detect it with the
naked eye.
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