CK-12 Chemistry Concepts - Intermediate Answer Key Chapter 11: Chemical Reactions 11.1 Word Equations Practice Questions Read the material at the link below and do the practice problems: http://www.dynamicscience.com.au/tester/solutions/chemistry/chemical%20equations.ht m Answers Answers can be seen when you click on “Solution”. Review Questions 1. Write the generic form of a chemical reaction. 2. What are reactants? 3. What are products? Answers 1. Reactants → Products 2. The starting materials for the process. 3. The materials formed by the reaction. 11.2 Chemical Equations Practice Questions Watch the video at the link below and do the examples seen in the video: http://www.youtube.com/watch?v=lSoRj_iBwYc Answers 1 Answers are provided as part of the video. Review Questions 1. 2. 3. 4. What does a skeleton equation tell you? Why would you want to know the physical state of materials? What does the symbol → mean? If I see Δ over the arrow, what will I do? Answers 1. What chemicals are involved, but not how much of each. 2. So you know how best to handle the materials and what to expect from the reaction. 3. It indicates that the reactants on the left of the arrow produce something found on the right of the arrow. 4. Heat the reaction. 11.3 Balancing Equations Practice Questions Get some experience in balancing chemical equations at the following web site: http://www.sciencegeek.net/APchemistry/APtaters/EquationBalancing.htm Answers Answers given at the web site Review Questions 1. What is the law of conservation of mass? 2. How did Dalton describe he profess of a chemical reaction? 3. Why don’t we change the subscripts in order to balance an equation? Answers 1. Matter can neither be created nor destroyed. 2. Atoms can be rearranged. 2 3. The subscripts indicate the composition of the molecule, not how many molecules are present. 11.4 Combination Reactions Practice Questions Complete the reactions and balance the equations on the worksheet at the link below: http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet2.pdf Answers Answers are on the worksheet. Review Questions 1. What are combination reactions? 2. Write the product of the following reaction: Mg + H2O → 3. Is CH4 + 2O2 → CO2 + 2H2O a combination reaction? Explain your answer. Answers 1. When two or more substances combine to form a new substance. 2. Mg(OH)2 3. No, two substances ere formed. In a combination reaction, only one substance is formed. 11.5 Decomposition Reactions Practice Questions Write the reactions (including names and balanced equations) as requested on the following web site: http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet3.pdf Answers 3 Answers are given on the worksheet. Review Questions 1. What is a decomposition reaction? 2. What is usually needed for a decomposition reaction to take place? 3. Are elements always the product of a decomposition reaction? Answers 1. A reaction in which a substance breaks down to form two or more substances. 2. An input of energy (heat, light, electricity). 3. No, sometimes other compounds are formed. 11.6 Combustion Reaction Practice Questions Write the reactions and balance the equations for the questions on the sheet found on this web site: http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet6.pdf Answers Answers are given on the sheet Review Questions 1. What is needed for a combustion reaction to take place? 2. What is formed in any combustion reaction? 3. Mercury reacts with oxygen to form mercuric oxide. Is this a combustion reaction? 4. What are the products of any combustion reaction involving a hydrocarbon? Answers 1. Oxygen. 2. Heat and light are released. 4 3. Yes, because oxygen is needed, although the reactions does not produce heat and light. 4. Water and carbon dioxide. 11.7 Single-Replacement Reactions Practice Questions Read the material at the link below and do the practice problems: http://www.chemteam.info/Equations/SingleReplacement.html Answers Answers given on the web site Review Questions 1. 2. 3. 4. What is a metal replacement reaction? Will a non-metal replace a metal? What is the most reactive halogen? What products will I get if I add potassium metal to water? Answers 1. 2. 3. 4. Where one metal replaces another metal. No. Fluorine. KOH and H2 gas. 11.8 Activity Series Practice Questions Take the quiz on the web site below: http://www.sophia.org/chemical-reactions-activity-series-concept Answers 5 Answers given on web site. Review Questions 1. What does the activity series tell us? 2. Can a metal undergo any of the reactions listed below it in the series? 3. List two metals that cobalt will displace and tow that will displace it. Answers 1. Relative reactivities of metals and halogens 2. Yes. 3. Cobalt will displace any metal listed below it and will be displaced by any metal above it. 11.9 Double-Replacement Reactions Practice Questions Read the material at the web site below and do the practice problems: http://www.chemteam.info/Equations/DoubleReplacement.html Answers Answers are provided on the web site. Review Questions 1. What are the usual reactants in a double-replacement reaction? 2. List the three possible types of products. 3. Why would you not expect two ionic products? Answers 1. Ionic compounds. 2. Gases, solids, or molecular compounds. 3. The reactants are all ions; you could not tell a reaction had taken place if only ions were present. 6
