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90 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 9
Write the skeleton equation with the correct formulas.
Na 2 S(aq) ϩ HCl(aq) 0 NaCl(aq) ϩ H 2 S(g)
Add coefficients to write a balanced chemical equation.
Na 2 S(aq) ϩ 2HCl(aq) 0 2NaCl(aq) ϩ H 2 S(g)
Write the complete ionic equation, which includes all the ions.
2Na ϩ (aq) ϩ S 2Ϫ (aq) ϩ 2H ϩ (aq) ϩ 2Cl Ϫ (aq) 0
2Na ϩ (aq) ϩ 2Cl Ϫ (aq) ϩ H 2 S(g)
Remove the spectator ions to produce the net ionic equation.
S 2Ϫ (aq) ϩ 2H ϩ (aq) 0 H 2 S(g)
Practice Problems
8. Write balanced chemical, complete ionic, and net ionic equations for the reactions between the following substances, which
produce a gas.
a. hydrochloric acid and aqueous sodium cyanide, with production of hydrogen cyanide gas (HCN)
b. sulfuric acid (H 2 SO 4 ) and aqueous rubidium sulfide, with
production of hydrogen sulfide gas
Chapter 9 Review
9. Define chemical reaction. Where are the reactants and products
shown in an equation for a chemical reaction, and how are the
physical states indicated?
10. Compare and contrast word equations, skeleton equations, and
balanced chemical equations.
11. Briefly list the steps used in balancing a chemical equation.
12. Contrast synthesis, combustion, and decomposition reactions.
13. Contrast single-replacement and double-replacement reactions.
14. Define aqueous solution. What name is given to a solid that
forms when two aqueous solutions are mixed?
15. How do complete ionic and net ionic equations differ?
16. Name three typical types of products that may be formed in
double-replacement reactions.