MGS13 LEP PS C05 CHT A - Bridgeway

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. c. enzyme.

b. catalyst. d. fuel.

____ 4. CaCO3 represents a chemical a. symbol. c. subscript.

b. formula. 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 + O2 c. Na2O + O2

2 Na2O 2 NaO

b. 2 Na + O2 d. Na2 + O2

2 NaO Na2O2

____ 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.

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Name____________________________ Date ____________________ Class ____________

Chemical Reactions (continued)

____ 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 ice bath.

c. Heat the reaction flask on a hot plate.

b. Add a catalyst. d. Add an inhibitor.

____ 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. c. replacement reaction.

b. decomposition 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.

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Name____________________________ Date ____________________ Class ____________

Chemical Reactions (continued)

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 (CO2), and water (H2O), what elements were in the reactants? How do you know? ____________________________________________________________________________ ____________________________________________________________________________

24. Is the reaction that occurs in the diagram endothermic or exothermic? Explain. ____________________________________________________________________________ ____________________________________________________________________________

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Name____________________________ Date ____________________ Class ____________

Chemical Reactions (continued)

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 + O2 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? ____________________________________________________________________________ ____________________________________________________________________________

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Name____________________________ Date ____________________ Class ____________

Chemical Reactions (continued)

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.)

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