Name: 
 

8th Grade Review



Matching
 
 
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
 

 1. 

process that produces chemical change
 

 2. 

substance that slows down a chemical reaction
 

 3. 

reaction in which heat energy is absorbed
 

 4. 

substance that exists before a chemical reaction begins
 

 5. 

minimum amount of energy needed in order for a reaction to begin
 

 6. 

substance formed by a chemical reaction
 

 7. 

substance that speeds up a chemical reaction
 

 8. 

reaction in which heat energy is released
 

 9. 

a measure of how fast a reaction occurs
 
 
Tell whether each equation is either balanced or unbalanced.
a.
balanced
b.
unbalanced
 

 10. 

MgCO3 + 2HCl®MgCl2 + H2CO3
 

 11. 

2H2 + O2®H2O
 

 12. 

CaCl2®2Ca +Cl2
 

 13. 

Zn + 2HCl®ZnCl2 + H2
 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 14. 

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
 

 15. 

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
 

 16. 

You can slow down the rate of a reaction by ____.
a.
increasing concentration
c.
decreasing particle size
b.
increasing temperature
d.
adding an inhibitor
 

 17. 

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
 

 18. 

In an exothermic reaction, heat is ____.
a.
absorbed
c.
released
b.
conserved
d.
destroyed
 

 19. 

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
 

 20. 

A chemical that keeps food from spoiling is an example of ____.
a.
a catalyst
c.
a reactant
b.
an enzyme
d.
an inhibitor
 

 21. 

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
 

 22. 

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
 

 23. 

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
 

 24. 

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
 

 25. 

The presence of a(n) ____ speeds up a reaction.
a.
reactant
c.
product
b.
catalyst
d.
inhibitor
 

 26. 

Heat is absorbed during ____ reactions.
a.
activation
c.
enzyme
b.
endothermic
d.
exothermic
 

 27. 

Substances formed during chemical reactions are ____.
a.
catalysts
c.
reactants
b.
oxides
d.
products
 

 28. 

A ____ is a process in which new substances are formed.
a.
chemical reaction
c.
reactant
b.
catalyst
d.
subscript
 

 29. 

The melting of ice is an example of a(n) ____.
a.
chemical change
c.
exothermic reaction
b.
endothermic reaction
d.
physical change
 

 30. 

For a chemical reaction to begin, ____ is needed.
a.
combustion
c.
activation energy
b.
a catalyst
d.
a spark
 

 31. 

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
 

 32. 

Adding an inhibitor tends to ____ a reaction.
a.
slow down
c.
speed up
b.
stop
d.
reverse
 

 33. 

Chemical reactions usually speed up at ____ temperatures.
a.
Celsius
c.
higher
b.
lower
d.
absolute
 

 34. 

Reactants have their highest concentrations ____ a chemical change takes place.
a.
after
c.
both A and B
b.
before
d.
neither A nor B
 

 35. 

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
 

 36. 

Catalysts ____ the activation energy needed to start a chemical reaction.
a.
inhibit
c.
reduce
b.
increase
d.
balance
 

 37. 

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
 

 38. 

The ____ is a measure of how fast a reaction proceeds.
a.
rate of reaction
c.
activation energy
b.
catalyst effect
d.
concentration
 

 39. 

The size of the reactant particles can affect the ____ of a reaction.
a.
temperature
c.
concentration
b.
product
d.
rate
 

Completion
Complete each statement.
 

 40. 

The burning of paper is an example of a(n) ____________________ (physical change, chemical change, endothermic reaction).
 

 

 41. 

The molecule H2C2H3O2 has ____________________ (four, eleven, nine) atoms.
 

 

 42. 

In an endothermic reaction, ____________________ (inhibitor, energy, catalyst) is absorbed.
 

 

 43. 

A catalyst speeds up a reaction by reducing ____________________ (concentration, activation energy, temperature).
 

 

 44. 

Energy is released in a(n) ____________________ (exothermic, endothermic, reverse) reaction.
 

 

Essay
 

 45. 

Compare and contrast the effect of a catalyst on a chemical reaction with that of an inhibitor.
 

 46. 

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?
 

 47. 

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.
 

 48. 

What does the graph illustrate?
es048-1.jpg
 
 
Use the illustration showing the same reactants under different conditions to answer the following questions.
nar001-1.jpg
 

 49. 

What are the different conditions shown?
 

 50. 

Under which conditions does the reaction proceed at a faster rate? Why?
 
 
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.
 

 51. 

Zn + HCl®ZnCl2 + H2
 

 52. 

H2CO3®H2O + CO2
 

 53. 

Fe + 3O2®2Fe2O3
 

 54. 

BaCl2 + Na2SO4®BaSO4 +2NaCl
 

 55. 

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?
 

 56. 

How do you know that the spoiling of food involves a chemical reaction? What purpose does refrigerating food serve?
 

 57. 

Why do wood splinters burn faster than the log from which they came?
 

 58. 

What are enzymes? List two ways that your body uses enzymes.
 



 
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