Chemical Reactions. Chapter Test A. Multiple Choice. 1 Pearson Education, Inc., or its affiliates. All rights reserved.

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1 Name Date Class Chemical Reactions Chapter Test A Multiple Choice Write the letter of the correct answer on the line at the left. 1. Chemistry is a. a characteristic of a substance that can be observed without changing the substance into another substance. b. the study of matter and how matter changes. c. anything that has mass and takes up space. d. a rapid reaction between oxygen and a substance called a fuel. 2. The only sure evidence for a chemical reaction is a. the formation of a gas. b. a color change. c. the production of one or more new substances. d. changes in properties. 3. A material used to decrease the rate of a chemical reaction is a(n) a. inhibitor. b. catalyst. c. enzyme. d. fuel. 4. CaCO 3 represents a chemical a. symbol. b. formula. c. subscript. d. reaction. 5. Which is the correct chemical equation for the following statement? Sodium reacts with oxygen in a 2 to 1 ratio to produce sodium oxide. a. 4 Na + O 2 2 Na 2 O b. 2 Na + O 2 2 NaO c. Na 2 O + O 2 2 NaO d. Na 2 + O 2 Na 2 O 2 6. The principle of conservation of mass is true a. only for reactions that take place in open systems. b. only for reactions that take place in closed systems. c. for reactions in both open and closed systems. d. for no reactions at all. 7. In chemical reactions, what does the principle of conservation of mass mean? a. Matter is not created or destroyed. b. The total mass of the reactants is greater than the total mass of the products. c. The total mass of the reactants is less than the total mass of the products. d. Matter is not changed. 1

2 Name Date Class 8. Chemicals that act as biological catalysts by speeding up reactions in living things are called a. inhibitors. b. enzymes. c. fuels. d. reactants. 9. Which of the following is an example of how to supply activation energy to begin a reaction? a. Cool the reaction flask in an b. Add a catalyst. ice bath. c. Heat the reaction flask on a d. Add an inhibitor. hot plate. 10. A bottle of hydrogen peroxide that eventually turns into a bottle of water and oxygen gas is an example of a a. synthesis reaction. b. decomposition reaction. c. replacement reaction. d. precipitate reaction. Completion Fill in the line to complete each statement. 11. A precipitate is a(n) that forms from solution during a chemical reaction. 12. In a chemical equation, the substances written on the right side of the arrow are called. 13. The _ is the minimum amount of energy that must be added to start a chemical reaction. 14. A mistake in the design of an experiment that makes a certain result more likely is called experimental. 15. A reaction in which one element replaces another in a compound or in which two elements in different compounds trade places is called a(n) reaction. True or False If the statement is true, write true. If it is false, change the underlined word or words to make the statement true. 16. Physical changes occur when existing bonds break and new bonds form. 17. The amount of matter in a chemical reaction changes. 18. Synthesis is the process of making a more complex compound from simpler substances. 19. Subjective reasoning relies on gathering and evaluating evidence. 20. The rate of a chemical reaction is independent of temperature. 21. A chemical reaction may be detected by observing changes in the properties of matter. 2

3 Name Date Class Using Science Skills Use the diagram to answer each question. 22. When the candle was lit, a pool of liquid wax formed in the area around the wick, and then spilled over the side and solidified. Does this observation refer to a physical change or a chemical change? Explain. 23. If the products formed from the burning candle are mostly carbon (C), carbon dioxide (CO 2 ), and water (H 2 O), what elements were in the reactants? How do you know? 24. Is the reaction that occurs in the diagram endothermic or exothermic? Explain. 3

4 Name Date Class Essay Write an answer for each of the following questions on a separate sheet of paper. 25. Explain which bonds are broken and which bonds are formed during the reaction of magnesium and oxygen to form magnesium oxide. Identify which substances are compounds and which are elements. 2 Mg + O 2 2 MgO 26. For each situation described below, tell whether the reaction is endothermic or exothermic. Explain your reasoning in terms of the energy of the reactants and products. A) A log burns in a fireplace, giving off gases and leaving behind ash. B) When vinegar and baking soda are mixed, new substances form and the solution becomes cooler. Using Science Skills Use the diagram to answer each question. 27. What type of chemical reaction is represented in the diagram? Explain. 28. What is the purpose of the burning splint in the reaction? 29. What is the first rule you should follow if you have an accident while doing this lab? 4

5 Name Date Class Essay Write an answer for each of the following questions on a separate sheet of paper. 30. Relate the writing and balancing of a chemical equation to the principle of conservation of mass. 31. Describe the difference between a synthesis reaction and a decomposition reaction. 32. Explain each of the following in terms of factors that affect the rate of a chemical reaction. A) Chemical reactions in living things would not be possible without the enzymes found in cells. B) Wood burns at a steady rate, but sawdust may explode if a spark ignites it. (Sawdust is tiny particles of wood made from sawing wood.) 5