Answers to Questions & Problems in Textbook - Chapter 8

1. Water is the most universal of all liquids. Water has a relatively large heat capacity, and a relatively large liquid range, which means it can absorb the heat liberated by many reactions while still remaining in the liquid state. Water is very polar and dissolves well both ionic solutes and solutes with which it can hydrogen bond (this is especially important to the biochemical reactions of the living cell).
2. in your text
3. in your text
4. When an electrolyte such as NaCl (sodium chloride) is dissolved in water, the resulting solution consists of separate, individual, discrete sodium ions (Na+) and separate, individual, discrete chloride ions (Cl-). There are no identifiable NaCl units in such a solution.
5. A substance is said to be a strong electrolyte if each unit of the substance produces separated, distinct ions when the substance is dissolved in water. NaCl and KNO3 are both strong electrolytes.
6. NaNO3 must be soluble in water.
7. in your text
8.
1. in your text
2. soluble (potassium salt)
3. in your text
4. insoluble (hydroxide compound)
5. in your text
6. soluble (ammonium salt)
7. in your text
8. insoluble (exception for sulfate salts)
9.
1. in your text
2. rule 6: most carbonates are only slightly soluble.
3. in your text
4. rule 3: exception to the rule for chlorides.
10.
1. in your text
2. AgI
3. in your text
4. Fe(OH)3
5. in your text
6. BaCO3
11.
1. in your text
2. (NH4)2S + Pb(NO3)2 --> CoS + 2NH4Cl
3. in your text
4. CaCl2 + K2CO3 --> CaCO3 + 2KCl
5. in your text
6. Na3PO4 + CrCl3 --> 3NaCl + CrPO4
12.
1. in your text
2. Ca(NO3)2 + H2SO4 --> CaSO4 + 2HNO3
3. Pb(NO3)2 + H2SO4 --> PbSO4 + 2HNO3
13.
1. in your text
2. FeCl3 + 3NaOH --> Fe(OH)3 + 3NaCl
3. CuSO4 + Na2CO3 --> CuCO3 + Na2SO4
14.
1. in your text
2. 2Fe3+ + 3CO32- --> Fe2(CO3)3
3. in your text
4. 3Co2+ + 3PO43- --> Co3(PO4)2
5. in your text
6. Pb2+ + 2Br- --> PbBr2
15. Ag+ + Cl- --> AgCl, Pb2+ + 2Cl- --> PbCl2, Hg22+ + 2Cl- --> Hg2Cl2
16. Ca2+ + C2O42- --> CaC2O4
17. Strong acids are acids that ionize completely in water. The strong acids are also strong electrolytes.
18. in your text
19. in your text
20. HBr --> H+ + Br-, HClO4 --> H+ + ClO4-
21. in your text
22.
1. in your text
2. HClO4 + NaOH --> H2O + NaClO4
3. in your text
4. H2SO4 + 2CsOH --> 2H2O + Cs2SO4
23.
1. in your text
2. RbOH + HNO3 --> H2O + RbNO3
3. in your text
4. KOH + HCl --> H2O + KCl
24. A driving force, in general, is an event which tends to help convert the reactants of a process into the products. Some elements (metals) tend to lose electrons, while other elements (nonmetals) tend to gain electrons. A transfer of electrons from atoms of a metal to atoms of a nonmetal would be favorable, and would result in a chemical reaction. A simple example of such a process is the reaction of sodium with chlorine: sodium atoms tend to each lose one electron (to form Na+), whereas chlorine atoms tend to each gain one electron (to form Cl-). The reaction of sodium metal with chlorine gas represents a transfer of electrons from sodium atoms to chlorine atoms to form sodium chloride.
25. in your text
26. in your text
27. in your text
28.
1. 2, 1, 2
2. 4, 1, 2
3. 6, 1, 2
4. 4, 1, 1
29.
1. in your text
2. 1, 2, 1, 1
3. in your text
4. 2, 1, 2
5. in your text
30. A double-displacement reaction has the form AB + CD --> AD + CD. In a double-displacement reaction, when two solutions of ionic solutes are mixed, the positive ions of the two solutes exchange anions (this presupposed that some driving force is present which causes a detectable reaction to occur). A single-displacement reaction has the form A + BC --> AC + B. In a single displacement reaction, a new element replaces a less active element in its compound.
31. in your text
32. For each reaction, the type of reaction is first identified, followed by some of the reasoning that leads to this choice (three may be more than one way in which you can recognize a particular type of reaction).
1. precipitation (BaSO4 is the precipitate)
2. oxidation-reduction (Zn changes from the elemental to the combines state; hydrogen changes from the combines to the elemental state)
3. precipitation (AgCl is insoluble)
4. acid-base (HCl is an acid; KOH is a base; water and salt are produced)
5. oxidation-reduction (Cu changes from the combines to the elemental state; Zn changes from the elemental to the combines state)
6. acid-base (the H2PO4- ion behaves as an acid; NaOH behaves as a base; a salt and water are produced)
7. precipitation & acid-base [Ca(OH)2 is a base; H2SO4 is an acid; a salt (Ca(SO)4 is insoluble); and water are produced]
8. oxidation-reduction (Mg changes from the elemental to the combined state; Zn changes from the combined to the elemental state)
9. precipitation (BaSO4 is insoluble)
33. all parts are in your text
34. A synthesis reaction represents the production of a given compount from simpler substances (either elements or simpler comounds). For example, O2(g) + 2F2(g) --> 2OF2(g) represents a simple synthesis reaction. Synthesis reaction may often (but not necessarily always) also be classified in other ways. For example, the reaction C(s) + O2(g) --> CO2(g) could also be classified as an oxidation-reduction reaction, or as a combustion reaction (a special sub-classification of oxidation-reduction reaction that produces a flame). As another example, the reaction 2Fe(s) + 3Cl2(g) --> 2FeCl3(s) is a synthesis reaction that also is an oxidation-reduction reaction.
35. in your text
36.
1. in your text
2. 2, 19, 12, 14
3. 1, 9, 6, 6
37.
1. in your text
2. 1, 3, 2, 3
3. 2, 5, 4, 6
38.
1. in your text
2. 2, 1, 2
3. in your text
4. 2, 3, 2
5. 2, 1, 1
39.
1. in your text
2. 1, 1, 1
3. in your text
4. 1, 1, 4
5. 3, 1, 4
40. A molecular equation uses the normal, uncharged formulas for the compounds involved. The complete ionic equation shows the compounds involves broken up into their respective ions (all ion present are shown). The net ionic equation shows only those ions which combine to form a precipitate, a gas, or a nonionic product such as water. The net ionic equation shows most clearly the species that are combining with each other.
41.
1. in your text
2. calcium ion would precipitate when treated with solutions containing sulfate ion, carbonate ion, and phosphate ion. 3, 2, 1
3. in your text
4. sulfate ion would precipitate when treated with solutions containing barium ion, calcium ion, or lead (II) ion. 1, 1, 1
5. in your text
6. silver ion would precipitate when treated with solutions containing chloride ion, sulfide ion, or carbonate ion. 2, 1, 1
42.
1. in your text
2. Hg22+ (aq) + 2 Cl-(aq) --> Hg2Cl2(s)
3. in your text
4. Cu 2+(aq) + S2-(aq) --> CuS (s)
5. in your text
6. Ca2+(aq) + CO32-(aq) --> CaCO3(s)
7. Au3+(aq) + 3OH-(aq) --> Au(OH)3 (s)
43.
1. in your text
2. 1, 1, 2, 1, BaSO4(s)
3. in your text
4. 2, 1, 2, 1, CaCl2(aq)
44. For each cation, the precipitates that form with the anions listen in the right-hand column are given below. If no formula is listed, it should be assumed that that anion does not form a precipitate with the particular cation.
1. Ag+ AgCl, Ag2CO3, AgOH, Ag3PO4, Ag2S, Ag2SO4
2. Ba2+, BaCO3, Ba(OH)2, Ba3(PO4)2, BaS, BaSO4
3. Ca2+, CaCO3, Ca(OH)2, Ca3(PO4)2, CaS, CaSO4
4. Fe3+, Fe2(CO3)3, Fe(OH)3, FePO4, Fe2S3
5. Hg22+, Hg2Cl2, Hg2CO3, Hg2(OH)2, (Hg2)3(PO4)2, Hg2S
6. Na+, all common salts soluble
7. Ni2+, NiCO3, Ni(OH)2, Ni3(PO4)2, NiS
8. Pb2+, PbCl2, PbCO3, Pb(OH)2, Pb3(PO4)2, PbS, PbSO4
45.
1. in your text
2. CuSO4 + (NH4)2CO3 --> CuCO3 + (NH4)2SO4
3. in your text
4. no reaction
5. in your text
6. SnCl4 + 4NaOH --> Sn(OH)4 + 4NaCl
46.
1. in your text
2. 3Ca3+ + 2PO43- --> Ca3(PO4)2
3. in your text
4. Fe3+ + 3OH- --> Fe(OH)3
47. skip this question
48.
1. in your text
2. one
3. in your text
4. two
5. in your text
49.
1. in your text
2. one; F + e- --> F-
3. in your text
4. one; Cl + e- --> Cl-
5. two; S + 2e- --> S2-
50.
1. in your text
2. precipitation, double replacement
3. in your text
4. oxidation-reduction, decomposition
5. oxidation-reduction, combustion