Equations Exercises, continued from page 1
Answers to Exercises
1. single displacement
2. double displacement
3. decomposition
4. combination
5. single displacement
6. combustion
7. double displacement
8. combination
9. decomposition
10. a) double displacement: NaHCO3 (s) + HC2H3O2 (aq) ––�?gt; H2CO3 (aq) + NaC2H3O2 (aq)
b) decomposition: H2CO3 (aq) ––�?gt; CO2 (g) + H2O (l)
(See note at bottom)
11. Fe2O3 (s) + 3 H2 (g) ––�?gt; 2 Fe (s) + 3 H2O (l)
12. 4 Al (s) + 3 O2 (g) ––�?gt; 2 Al2O3 (s)
13. Zn(NO3)2 (aq) + 2 NaOH (aq) ––�?gt; 2 NaNO3 (aq) + Zn(OH)2 (s)
14. 2 CCl4 (g) + O2 (g) ––�?gt; 2 COCl2 (g) + 2 Cl2 (g)
15. N2O5 (g) + H2O (l) ––�?gt; 2 HNO3 (aq)
16. PCl5 (l) + 4 H2O (l) ––�?gt; H3PO4 (aq) + 5 HCl (aq)
17. 2 C6H14 (l) + 19 O2 (g) ––�?gt; 12 CO2 (g) + 14 H2O (l)
18. 3 NO2 (g) + H2O (l) ––�?gt; 2 HNO3 (aq) + NO (g)
19. 2 CH3CH2OH (l) + 6 O2 (g) ––�?gt; 4 CO2 (g) + 6 H2O (g)
20. 3 Cu (s) + 8 HNO3 (aq) ––�?gt; 3 Cu(NO3)2 (aq) + 2 NO (g) + 4 H2O (l)
21. Single Displacement: 2 Al (s) + 3 CuSO4 (aq) ––�?gt; 3 Cu (s) + Al2(SO4)3 (aq)
22. Double Displacement: CdCl2 (aq) + Na2S (aq) ––�?gt; 2 NaCl (aq) + CdS (s)
23. Combination: SO3 (g) + H2O (l) ––�?gt; H2SO4 (aq)
24. Decomposition: 2 H2O2 (aq) ––�?gt; 2 H2O (l) + O2 (g)
25. Double Displacement: Pb(NO3)2 (aq) + 2 NaCl (aq) ––�?gt; 2 NaNO3 (aq) + PbCl2 (s)
26. Combustion: 2 C40H82 (s) + 121 O2 (g) ––�?gt; 80 CO2 (g) + 82 H2O (g)
27. Combination: 2 H2 (g) + O2 (g) ––�?gt; 2 H2O (l)
28. Single Displacement: 2 Na (s) + 2 H2O (l) ––�?gt; H2 (g) + 2 NaOH (aq)
29. Double Displacement: 2 Al(OH)3 (s) + 3 H2SO4 (aq) ––�?gt; 6 H2O (l) + Al2(SO4)3 (aq)
30. Combination: 3 Mg (s) + N2 (g) Mg3N2 (s)
Note for Question 10
The following products are unstable and decompose immediately upon formation:
carbonic acid, H2CO3 (aq) ––�?gt; CO2 (g) + H2O (l)
sulfurous acid, H2SO3 (aq) ––�?gt; SO2 (g) + H2O (l)
ammonium hydroxide, NH4OH (aq) ––�?gt; NH3 (g) + H2O (l)
When you form any of these compounds, write the decomposition products instead, since these are what will actually be formed in the reaction.