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Chapter 21 Review

Chapter 21 Review

Vocabulary review

Match the following terms with the correct definition. There is an extra definition that will not match any term

Concept review

1. Are combustion reactions usually exothermic or endothermic?

2. The formation of rust is represented by the following reaction:4Fe(s) + 3O2(g) 2Fe2O3(s) + energy

a. Classify this reaction as either: single-displacement,decomposition, addition, combustion or double-displacement.

b. Is this reaction exothermic or endothermic?

3. What conditions must be met in order for a reaction to beconsidered exothermic?

4. A reaction that requires more energy to break the bonds in thereactants than is released when new bonds are formed in theproducts is a(n): a. MRE reaction.b. endothermic reaction.c. silver reaction.d. exothermic reaction.

Set One Set Two1. combustion reaction a. A large molecule with repeating units of

smaller molecules1. precipitate a. A reaction that uses more energy than it

produces

2. decomposition reaction b. A molecule that is used to speed up reactions 2. single-displacement reaction

b. AB + CD AD + CB

3. double-displacement reaction

c. The process of attaching small molecule units together to make a large molecule

3. endothermic reaction c. A + B AB

4. polymer d. AB A + B 4. addition reaction d. AX + B BX + A

5. polymerization e. AB + CD AD + CB 5. exothermic reaction e. The insoluble product of a double-displacement reaction

f. A reaction that is used to obtain energy from fuel

f. A reaction that produces more energy than it uses

Chapter 21 Review

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Problems

1. Identify the following reactions as: addition, decomposition,single-displacement, double-displacement, or combustionreactions.a. NaS (aq) + ZnNO3(aq) NaNO3(aq) + ZnS (s) b. 6Li(s) + N2 2Li3N c. 2KClO3 2KCl + 3O2 d. 2C3H7OH + 9O2 6CO2 + 8H2O e. Mg + 2AgNO3 Mg(NO3)2 + 2Ag

2. Complete the reactions below. You are not required to balancethis set.a. H2SO4(aq) + BaCl(aq) b. ZnSO4(aq) + Na3PO4(aq) c. HCl (aq) + K2SO3 d. SnCl2 + Fe2(SO4)3

3. Use the solubility rules to identify the precipitate, if any, foreach reaction in question 2.

4. Complete and balance the following reactions:a. Fe(s) + CuCl2(aq) b. C2H6(g) + O2(g)c. NaCl(aq) + NH4OH(aq)d. H2Oe. Cu(s) + O2(g)f. Al2O3g. Mg(s) + HCl(aq)h. LiNO3(aq) + MgCl2(aq)

�Applying your knowledge

1. �Many drain cleaners are a mixture of sodium hydroxide andaluminum filings. When these two substances mix in water,they react to produce enough heat to melt the fat in a cloggeddrain. The bubbles produced are hydrogen gas. The completereaction occurs in two steps:step 1: Al(s) + NaOH(aq) → Al(OH)3(s) + Na+ (aq)

step 2: Na+(aq) + H2O → Na2O(s) + H2(g)

a. Classify step 1 of the reaction as: addition, single-displacement, double-displacement or decomposition.

b. Is this an endothermic or an exothermic reaction?c. Balance each equation for each step of the reaction.

2. �Propane, C3H8, is a gas that is used by cooks and campersevery day. It is burned in oxygen in order to cook food, provideheat and light, and even to run refrigerators in areas that do nothave electricity. Write the complete, balanced equation for thecombustion of propane.

3. �Light bulb filaments are made of the element tungsten.When this metal is heated, it usually forms an oxide with theoxygen in the air. This causes the metal to become brittle andfall apart. Can you explain why the filament of tungsten insideof a light bulb does not form an oxide? (Hint: think about thestructure of a light bulb.)