Answers to Questions & Problems in Textbook - Chapter 7

1. A change in color, formation of a solid, evolution of gas, and absorption or evolution of heat. Other bits of evidence that might also be observed include appearance or disappearance of a characteristic odor, or separation of ther eaction mixtures into layers of visibly different composition.
2. in your text
3. The fact that the material in the drain, which did not dissolve in water, dissolves when the drain cleaner is added, suggests that rather than simple dissolving, the material in the drain has undergone a chemical change which makes it soluble. You may also have noticed that the drain cleaner evolved heat when added to the drain: evolution or absorption of heat is also often a sign of a chemical reaction.
4. in your text
5. reactants, products
6. in your text
7. gaseous
8. in your text
9. CaCO
3 --> CaO + CO2
10. C3H8(g) + 5 O2(g) --> 3 CO2(g) + 4 H2O(g)
11. 2 H2(g) + O2(g) --> 2 H2O(g)
12. (NH
4)2CO3(s) --> 2 NH3(g) + CO2(g) + H2O(g)
13. 2 Ag
2O(s) --> 4 Ag(s) + O2(g)
14. CO
(g) + 2 H2(g) --> CH3OH(L)
15. B
2O3(s) + 3 Mg(s) --> 2 B(s) + 2 MgO(s)
16. Ca
(s) + 2 H2O(L) --> Ca(OH)2(s) + H2(g)
17. P
4(s) + 6 Cl2(g) --> 4 PCl3(s)
18. Mg(OH)
2(s) + 2 HCl(aq) --> MgCl2(aq) + 2 H2O(L)
19. NH4NO3(s) --> N2O(g) + 2 H2O(g)
20. 2 H
2S(g) + 3 O2(g) --> 2 SO2(g) + 2 H2O(g)
21. 2 C
2H2(g) + 5 O2(g) --> 4 CO2(g) + 2 H2O(g)
22. 2 Fe
2O3(s) + 3 CO(g) --> 4 Fe(s) + 3 CO2(g)
23. 3 BaO
(s) + 2 Al(s) --> 3 Ba(s) + Al2O3(s)
3 CaO
(s) + 2 Al(s) --> 3 Ca(s) + Al2O3(s)
3 SrO
(s) + 2 Al(s) --> 3 Sr(s) + Al2O3(s)
24. 3 O2(g) --> 2 O3(g)
25. CH4(g) + 4 Cl2(g) --> CCl4(L) + 4 HCl(g)
26. NH
3(g) + HNO3(aq) --> NH4NO3(s)
27. 2 PbS + 3 O
2 --> 2 PbO(s) + 2 SO2(g)
2 PbO
(s) + C(s) --> 2 Pb(s) + CO2(g)
28. Xe
(g) + 2 F2(g) --> XeF4(s)
29. 2 NH
4NO3(s) --> 2 N2(g) + O2(g) + 4 H2O(g)
30. 2 Ag
(s) + 2 HNO3(aq) --> 2 AgNO3(aq) + H2(g)
31. formula
32. in your text
33.
in your text
2Ag + H
2S --> Ag2S + H2
in your text
Cl
2 + 2KI --> 2KCl + I2
34.
in your text
3KBr + H
3PO4 --> K3PO4 + 3HBr
in your text
equation is already balanced
35.
in your text
MnO
2 + 2Mg --> Mn + 2MgO
in your text
4NH
3 + 3Cl2 --> 3NH4Cl + NCl3
36.
  1. in your text
  2. PbCl2 + K2SO4 --> PbSO4 + 2KCl
  3. in your text
  4. CaC2 + 2H2O --> Ca(OH)2 C2H2
37. in your text
38. KNO
3 + C --> K2CO3 + CO + N2
39. in your text
40. 2H
2 + CO --> CH3OH
41. in your text
42. Fe
3O4 + 4H2 --> 3Fe + 4H2O
Fe
3O4 + 4CO --> 3Fe + 4CO2
43. in your text
44. in your text
45. 2H
2O2 --> 2H2O + O2
46. CaSiO
3 + 6HF --> CaF2 + SiF4 + 3H2O
47. Many over-the-counter antacids contain either carbonate ion (
CO32−) or hydrogen carbonate ion (HCO3). When either of these encounter stomach acid (primarily HCl), carbon dioxide gas is released.
48. in your text
49. Mg + O
2 --> MgO
50. in your text
51. PbS + O
2 --> PbO + SO2
52. Using the data to determine the empirical formula results in C
2HNO2.
Then using the molar mass of 213 allows you to determine the molecular formula is C
6H3N3O6
Thus the balanced equation: C
6H6 + 3HNO3 --> C6H3N3O6 + 3H2O