Matching
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Match each item with the correct term below. a. | activation energy | f. | inhibitor | b. | catalyst | g. | product | c. | chemical
reaction | h. | rate of
reaction | d. | endothermic reaction | i. | reactant | e. | exothermic
reaction |
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1.
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process that produces chemical change
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2.
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substance that slows down a chemical reaction
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3.
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reaction in which heat energy is absorbed
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4.
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substance that exists before a chemical reaction begins
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5.
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minimum amount of energy needed in order for a reaction to begin
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6.
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substance formed by a chemical reaction
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7.
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substance that speeds up a chemical reaction
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8.
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reaction in which heat energy is released
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9.
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a measure of how fast a reaction occurs
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Tell whether each equation is either balanced or unbalanced.
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10.
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MgCO3 + 2HCl®MgCl2 +
H2CO3
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11.
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2H2 + O2®H2O
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12.
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CaCl2®2Ca +Cl2
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13.
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Zn + 2HCl®ZnCl2 +
H2
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Multiple Choice Identify the
choice that best completes the statement or answers the question.
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14.
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Evidence that a chemical change has occurred includes a ____.
a. | change in state | c. | change in shape | b. | change in size | d. | change in color |
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15.
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An oven’s high temperature speeds up chemical reactions because heat
____.
a. | lowers the activation energy | b. | activates catalysts | c. | makes more molecules
collide with each other | d. | reduces the particle size of the
reactants |
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16.
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You can slow down the rate of a reaction by ____.
a. | increasing concentration | c. | decreasing particle
size | b. | increasing temperature | d. | adding an inhibitor |
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17.
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Which of the following is not an example of an exothermic reaction?
a. | the splitting of water into hydrogen and oxygen | b. | fireworks
exploding | c. | fish that emit light | d. | propane and oxygen changing into carbon dioxide
and water |
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18.
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In an exothermic reaction, heat is ____.
a. | absorbed | c. | released | b. | conserved | d. | destroyed |
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19.
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Activation energy is necessary for a chemical reaction to occur because
____.
a. | breaking bonds requires energy | b. | some reactions happen at cold
temperatures | c. | all reactions are endothermic | d. | forming bonds requires
energy |
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20.
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A chemical that keeps food from spoiling is an example of ____.
a. | a catalyst | c. | a reactant | b. | an enzyme | d. | an inhibitor |
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21.
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Presence of a catalyst ____.
a. | stops a reaction | c. | slows down a reaction | b. | raises the
activation energy needed | d. | reduces the activation energy needed |
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22.
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To check whether an equation is balanced, ____.
a. | add the number of reactants to the number of products | b. | make sure the masses
of the reactants and products are the same | c. | count the number of each type of atom on each
side | d. | check to see if the reaction is endothermic or
exothermic |
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23.
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Energy is usually only shown with the products in an equation for ____.
a. | an endothermic reaction | c. | an exothermic
reaction | b. | a synthesis reaction | d. | activation energy |
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24.
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The only balanced equation shown is ____.
a. | H2 + O2 ®H2
O | c. | Ag
+ H2S®Ag2S + H2 | b. | AgNO3 +
NaI®AgI + NaNO3 | d. | Na + Cl2®NaCl |
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25.
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The presence of a(n) ____ speeds up a reaction.
a. | reactant | c. | product | b. | catalyst | d. | inhibitor |
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26.
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Heat is absorbed during ____ reactions.
a. | activation | c. | enzyme | b. | endothermic | d. | exothermic |
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27.
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Substances formed during chemical reactions are ____.
a. | catalysts | c. | reactants | b. | oxides | d. | products |
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28.
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A ____ is a process in which new substances are formed.
a. | chemical reaction | c. | reactant | b. | catalyst | d. | subscript |
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29.
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The melting of ice is an example of a(n) ____.
a. | chemical change | c. | exothermic reaction | b. | endothermic reaction | d. | physical change |
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30.
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For a chemical reaction to begin, ____ is needed.
a. | combustion | c. | activation energy | b. | a catalyst | d. | a spark |
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31.
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The rate of reaction in a chemical change can be measured by how fast a(n) ____
appears.
a. | reactant | c. | exotherm | b. | activator | d. | product |
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32.
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Adding an inhibitor tends to ____ a reaction.
a. | slow down | c. | speed up | b. | stop | d. | reverse |
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33.
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Chemical reactions usually speed up at ____ temperatures.
a. | Celsius | c. | higher | b. | lower | d. | absolute |
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34.
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Reactants have their highest concentrations ____ a chemical change takes
place.
a. | after | c. | both A and B | b. | before | d. | neither A nor B |
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35.
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A higher concentration of reactant will speed up a chemical reaction because
there will be more ____ between the reactant particles.
a. | combustion | c. | bonds | b. | space | d. | collisions |
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36.
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Catalysts ____ the activation energy needed to start a chemical reaction.
a. | inhibit | c. | reduce | b. | increase | d. | balance |
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37.
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To check that an equation is balanced, count the number of ____ on each side of
the equation.
a. | ions | c. | atoms of each type | b. | molecules | d. | types of
elements |
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38.
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The ____ is a measure of how fast a reaction proceeds.
a. | rate of reaction | c. | activation energy | b. | catalyst effect | d. | concentration |
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39.
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The size of the reactant particles can affect the ____ of a reaction.
a. | temperature | c. | concentration | b. | product | d. | rate |
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Completion Complete each
statement.
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40.
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The burning of paper is an example of a(n) ____________________ (physical
change, chemical change, endothermic reaction).
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41.
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The molecule H2C2H3O2 has
____________________ (four, eleven, nine) atoms.
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42.
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In an endothermic reaction, ____________________ (inhibitor, energy, catalyst)
is absorbed.
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43.
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A catalyst speeds up a reaction by reducing ____________________ (concentration,
activation energy, temperature).
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44.
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Energy is released in a(n) ____________________ (exothermic, endothermic,
reverse) reaction.
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Essay
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45.
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Compare and contrast the effect of a catalyst on a chemical reaction with that
of an inhibitor.
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46.
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One sample of iron is left outdoors, while a second identical sample is kept
inside in a dry place. After a period of time, you observe more rust on the sample left outdoors than
on the sample kept inside. What can you infer from this observation?
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47.
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Two samples of iron are placed together outdoors. One sample is painted, the
other is not. What would you expect the conditions of the two samples to be like after a period of
time? Explain.
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48.
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What does the graph illustrate?
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Use the illustration showing the same reactants under different conditions to
answer the following questions.
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49.
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What are the different conditions shown?
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50.
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Under which conditions does the reaction proceed at a faster rate? Why?
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Applying Concepts Study each chemical equation. If the equation is
balanced, write “balanced” in the space provided. If it is not balanced, write
“unbalanced” and explain why it is not.
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51.
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Zn + HCl®ZnCl2 + H2
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52.
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H2CO3®H2O +
CO2
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53.
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Fe + 3O2®2Fe2O3
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54.
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BaCl2 + Na2SO4®BaSO4 +2NaCl
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55.
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What kind of reaction is displayed by a burning match? What role does rubbing
the match head on a rough surface have in the reaction?
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56.
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How do you know that the spoiling of food involves a chemical reaction? What
purpose does refrigerating food serve?
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57.
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Why do wood splinters burn faster than the log from which they came?
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58.
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What are enzymes? List two ways that your body uses enzymes.
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