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Energy in Chemical Changes Super Review

Total questions: 100

Worksheet time: 2hrs 40mins

Name
Class
Date
1.
Which of the following is NOT evidence that that a chemical reaction has occurred?
a)
produces light/heat
b)
production of a gas
c)
formation of a precipitate
d)
melting
2.

Which of the following is an example that includes evidence of a chemical reaction?

a)

A sample of zinc is placed in water and it settles to the bottom

b)

A solid block of ice is heated and it completely melts into a liquid.

c)

Sugar that is burned gives off an odor and turns brown and then black.

d)

A tomato is placed into a blender and chopped up into smaller pieces.

3.

Which of the following is an example that includes evidence of a chemical reaction?

a)

A sample of zinc is placed in water and it settles to the bottom

b)

A solid block of ice is heated and it completely melts into a liquid.

c)

Sugar that is burned gives off an odor and turns brown and then black.

d)

A tomato is placed into a blender and chopped up into smaller pieces.

4.
Hydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?
a)
The mass of the solution remains the same.
b)
 Phase changes are observed.
c)
 The color of the solution remains clear.
d)
The temperature of the solution increases. 
5.

Which of the following examples shows that a chemical reaction has occurred?

a)

A rock breaks into smaller pieces when it is struck with a hammer.

b)

Rust forms on a hammer that has been left outside to long.

c)

A cup of water turns pink when a few drops of red food coloring are added.

d)

A solid is formed when heat is removed from a sample of water.

6.

In a ___________change, a substance changes into a different substance.

a)

Physical

b)

Chemical

7.

What is the number before a chemical formula called?

Ex: 2H2 + O2 --> 2H2O

a)

Coefficient

b)

Subscript

c)

Atom

d)

Equation

8.

What is the little number after an element in a chemical equation called.

Example: H2

a)

Coefficient

b)

Subscript

c)

Atom

d)

Equation

9.

What is the role of the arrow sign in a chemical reaction?

a)

Making sure atom counts on each side are the same.

b)

Separating products and reactants.

c)

Showing which substances were in the container first and which substances were added later.

d)

Showing which substances are solids and which are liquids or gases.

10.

Identify the product(s) in the following chemical reaction:


Chromium oxide + Carbon → Chromium + Carbon monoxide

a)

Chromium and carbon.

b)

Chromium and carbon monoxide.

c)

Chromium and carbon dioxide.

d)

Chromium oxide and carbon.

11.

Identify the reactants(s) in the following chemical reaction:


Chromium oxide + Carbon → Chromium + Carbon monoxide

a)

Chromium and carbon.

b)

Chromium and carbon monoxide.

c)

Chromium and carbon dioxide.

d)

Chromium oxide and carbon.

12.

Are the number of atoms of each elements of the reactants the same as the products ?...

Al + O2 --> Al2O3

a)

Yes!

b)

No!

13.

Balance this equation:

MgCl2 --> Mg4+ Cl2

a)

It's already balanced.

b)

4MgCl2 --> Mg4+ 4Cl2

c)

4MgCl2 --> Mg4+ 5Cl2

14.

Balance this equation:

2Li + Cl2 -> LiCl

a)

2Li + Cl2 -> 4LiCl2

b)

2Li + Cl2 -> LiCl2

c)

2Li + Cl2 -> 2LiCl

15.

Is the following equation balanced or unbalanced ?

N2 +3 H2 --> 2NH3

a)

Balanced

b)

Unbalanced

16.
Is the following equation balanced or unbalanced ? 
Al + O2 --> Al2O3
a)
Balanced
b)
Unbalanced
17.
Which number should go in the blank?
_ H2 + O2 -> 2 H2O
a)
1
b)
2
c)
3
d)
0
18.

Which chemical equation best represents the Law of Conservation of Mass?

a)

H + O → H2O

b)

H2 + O2 → H2O

c)

2H2 + O2 → 2H2O

d)

H2 + O2 → 2H2O2

19.

Observe the reaction shown here. The formula for this equation is N2 + H2 → NH3N_2\ +\ H_2\ \rightarrow\ NH_3  . Does this represent a balanced equation that obeys the Law of Conservation of Mass?

a)

No. The reactants and products are not equal in numbers of atoms of each element. 

b)

Yes. The reactants and products are equal in numbers of atoms of each element. 

20.

Is this equation balanced?

a)

Yes

b)

No

21.
Balancing this reaction: ____ CH4 + ____ O2 ---> ____ CO2 + ____ H2O
a)
2,1,3,1
b)
1,2,1,2
c)
1,2,2,1
d)
2,1,1,2
22.

__NaClO3 --> __NaCl + __O2

a)

2,2,2

b)

2,2,3

c)

3,2,2

d)

1,2,3

23.

__Na + __Cl2 --> __NaCl

a)

1,1,2

b)

2,1,2

c)

2,1,1

d)

already balanced

24.

Combustion reactions will always involve

a)

Oxygen and a solid

b)

Liquid nitrogen and heat

c)

Oxygen and heat/energy

d)

CO and H2O

25.
At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?
a)
the product is doubled
b)
the product is half the mass of the reactants
c)
the mass is the same
d)
the mass changes depending on the reaction
26.

Which phrase describes what happens to atoms in a chemical reaction?

a)

never lost or gained, just rearranged

b)

sometimes lost, never rearranged

c)

sometimes lost, gained, or rearranged

d)

lost or gained, never rearranged

27.

The energy required to start a chemical reaction is ___.

a)

endothermic

b)

exothermic

c)

activation

d)

released

28.

Energy is _____ when new bonds form.

a)

absorbed

b)

released

c)

lost

d)

gained

29.

Energy is ______ when bonds break.

a)

gained

b)

lost

c)

released

d)

absorbed

30.

An _______ reaction is when more thermal energy is released than is absorbed.

a)

endothermic

b)

endergonic

c)

exothermic

d)

exergonic

31.

An _______ reaction is when more thermal energy is absorbed than is released.

a)

endothermic

b)

endergonic

c)

exothermic

d)

exergonic

32.

What is the measure of how fast molecules are moving?

a)

Speedometer

b)

Volume

c)

Temperature

d)

Thermometer

33.

In EXOTHERMIC reactions, energy is _____ from the reaction to the surroundings.

a)

Absorbed

b)

Released

c)

Eliminated

d)

Evaporated

34.

In ENDOTHERMIC reactions, energy is _____ by the reaction system from the surroundings.

a)

Absorbed

b)

Released

c)

Eliminated

d)

Obliterated

35.

Temperature usually _____ in EXOthermic reactions.

a)

Stays the same

b)

Increases

c)

Decreases

36.

Photosynthesis is an _____ reaction.

a)

EXOthermic

b)

ENDOthermic

37.

Cooking and baking are _____ reactions.

a)

EXOthermic

b)

ENDOthermic

38.

Fireworks are an _____ reaction.

a)

EXOthermic

b)

ENDOthermic

39.

The starting temperature of a reaction was 21 degrees Celsius and the ending temperature was 44 degrees Celsius. What type of reaction occurred?

a)

EXOthermic

b)

ENDOthermic

40.

A chemist is doing an ENDOthermic reaction. The starting temperature was 25 degrees Celsius. Which of the following would be a reasonable ending temperature

a)

44 degrees

b)

30 degrees

c)

15 degrees

d)

25 degrees

41.

If a chemical reaction produces light or sound, it is likely a _____ reaction.

a)

EXOthermic

b)

ENDOthermic

42.

What are the reactants in the chemical equation pictured?

a)

CH4 and CO2

b)

CH4 and O2

c)

CO2 and H2O

d)

O2 and H2O

43.

What are the products of the chemical reaction pictured?

a)

CH4 and CO2

b)

CH4 and O2

c)

CO2 and H2O

d)

O2 and H2O

44.

Combustion reactions will always involve

a)

Oxygen and a solid

b)

Liquid nitrogen and heat

c)

Oxygen and heat/energy

d)

CO and H2O

45.

When Lead Nitrate reacts with potassium iodide, Yellow precipitate of ............. is formed

a)

PbI2

b)

KNO3

c)

Pb(NO3)2

d)

PbIO3

46.

Balancing this reaction:

____ CH4 + ____ O2 ---> ___ CO2 + ____ H2O

a)

2,1,3,1

b)

1,2,1,2

c)

1,2,2,1

d)

2,1,1,2

47.

Balance this reaction:

____ Na3PO4 + ____ KOH ---> ____ NaOH + ____ K3PO4

a)

1,3,3,1

b)

1,3,2,1

c)

2,3,3,1

d)

1,1,3,1

48.

Balance this reaction:

____ NaF + ____ Br2 ---> ___ NaBr + ____ F2

a)

3,1,2,1

b)

1,2,3,4

c)

2,1,2,1

d)

1,2,1,2

49.
The red numbers in the image below represent ________
a)
subscripts
b)
coefficients
c)
I don't know, and don't want to try
d)
None of the answers are correct
50.
The blue numbers in the image below represent ________
a)
I don't know, and don't want to try
b)
coefficients
c)
subscripts
d)
none of the answers are correct
51.

Two chemicals reacted and one of the products stays dissolved in the solution. What symbol is used to indicate this?

a)

(s)

b)

(l)

c)

(aq)

d)

(g)

52.

Predict the products if Calcium Carbonate reacts with Silver Sulfate.

CaCO3 + Ag2SO4 → ?

a)

Ag2CO3 + Ca2SO4

b)

AgCO3 + CaSO4

c)

CaSO4 + Ag2CO3

d)

Ag(CO3)2 + CaSO4

53.

Predict the products for this substance: Al2O3 → ? + ?

a)

Al + O2

b)

O2 + Al3

c)

Al2 + O3

d)

Al + O

e)

Al3 + O

54.
Write a Balanced Equation for this reaction:
C2H4 + 2 O2 -->
a)
C2O2 + H4
b)
CO2 + HOH
c)
CO + H
d)
2 CO2 + 2H2O
55.
What are the correct formulas and coefficients for the products of the following single-replacement reaction?
Mg + Al(OH)3 →
a)
No Reaction
b)
Al + Mg(OH)3
c)
2 Al + 3 Mg(OH)2
d)
3 Al + MgOH3
56.
If an element is diatomic it should have a subscript of___
a)
2, always
b)
2, only when it is by itself
c)
it shouldn't have a subscript, it should have a coefficent
57.

CaCO3 represents a chemical

a)

formula

b)

subscript

c)

symbol

d)

reaction

58.

The minimum amount of energy needed to start a reaction is the.......

a)

activation energy

b)

exothermic energy

c)

chemical energy

d)

endothermic energy

59.

In chemical reactions, what does the law 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 poducts.

d)

Matter is not changed.

60.
How does an exothermic reaction feel?
a)
cold
b)
warm
c)
You can't feel it
d)
None of the above
61.
How do you know that energy is being absorbed during a chemical reaction?
a)
Temperature increases
b)
Temperature decreases
62.
How many total atoms are in K₂CO₃?
a)
6
b)
1
c)
4
d)
8
63.
How many atoms of phosphorous (P) are in Ba₃(PO₄)₂
a)
2
b)
3
c)
8
d)
6
64.
Which of the following models best demonstrates a balanced chemical equation?
a)
F
b)
G
c)
H
d)
J
65.
The formula below represents the most common carbohydrate known as glucose. Which information can be determined from the chemical formula?
C6H12O6
a)
The structural arrangement of the atoms in a glucose molecule
b)
The color of a glucose molecule
c)
The size of a glucose molecule
d)
The number of atoms of each element in a glucose molecule
66.
Which of the following is a sign that a chemical reaction has occurred?
a)
change in shape
b)
melting
c)
formation of a gas
d)
dissolving
67.
A common chemical reaction in plants.
a)
photosynthesis
b)
photographer
c)
alkali metals
d)
halogens
68.
What letter represents the energy of the products?
a)
A
b)
B
c)
C
d)
D
69.
What type of reaction is this?
a)
Endothermic
b)
Exothermic
70.
What letter represents the activation energy?
a)
A
b)
B
c)
C
d)
D
71.
What is the ΔH of this reaction?
a)
40 kJ
b)
20 kJ
c)
80 kJ
d)
60 kJ
72.

Which of the following reactions would NOT be representative of this graph?

a)

H2 (g) + O2 (g) --> H2O (l) + heat

b)

burning gasoline

c)

CaCO3 (s) --> CaO (s) + CO2 (g)

d)

the reaction between Mg and HCl (aq) - (done in lab)

73.
What is the sign of ΔH for all endothermic reactions?
a)
Positive
b)
Negative
74.
An enzyme speeds up a reaction by
a)
lowering the activation energy.
b)
raising the activation energy.
c)
releasing energy.
d)
absorbing energy.
75.
What is a substance called if it speeds up a chemical reaction?
a)
reusable
b)
catalyst
c)
specific
d)
fragile
76.

Compare the two pathways, which pathway shows the reaction that has taken place with the help of an enzyme?

a)

Pathway 1

b)

Pathway 2

c)

You cannot tell from these graphs.

d)

Both reactions involved an enzyme.

77.

At the end of this reaction, has energy been released or absorbed?

a)

Absorbed

b)

Released

c)

There is not enough information to tell.

d)

There is not change in the amount of energy in the system.

78.

Looking at the graph, how would you know which reaction took place with the help of an enzyme?

a)

The peak for the activation energy is lower.

b)

The peak for the activation energy is higher.

c)

There is less energy in the products than the reactants.

d)

There is no way to really tell which line on the graph shows a reaction that takes place with a reaction.

79.

What does the symbol (aq) stand for?

a)

Aquatic

b)

Aqueous

c)

Aqua

d)

Aquarium

80.

What does the symbol Δ represent?

a)

Change in energy

b)

Change in shape

c)

Change in color

d)

Change in attitude

81.

In the reaction of 1 mol of solid carbon with oxygen gas, the energy of the carbon dioxide gas produced is 393 kJ less than that of the reactants.

Is the reaction exothermic or endothermic?

a)

exothermic

b)

endothermic

c)

not enough information given.

82.

In the reaction of 1 mol of solid carbon with oxygen gas, the energy of the carbon dioxide gas produced is 393 kJ less than that of the reactants.

What is the value, in kilojoules, for the heat of reaction?

a)

ΔH = 393 kJ\Delta H\ =\ 393\ kJ  

b)

ΔH = −393 kJ\Delta H\ =\ -393\ kJ  

83.

True or false: ΔH for an endothermic reaction is a positive value.

a)

True

b)

False

84.

Examine the equation below. Is the reaction endothermic or exothermic, bond making or bond breaking, and why?

NaCl + AgF + energy -----> NaF + AgCl

a)

Exothermic reaction; no energy is shown on the product side so the energy will be released by the reactants to the products to help them make their bonds.

b)

Exothermic reaction; no energy is shown on the product side so the energy will be released by the reactants to the products to help the products break their bonds.

c)

Endothermic reaction; energy is a reactant so energy is being released by the reactants to the products to help them break their bonds.

d)

Endothermic reaction; energy is a reactant so energy is being taken in by the reactants to help them break their bonds.

85.

Examine the following reaction. Is it endothermic or exothermic and how do you know?

MgO + CaS ----> CaO + MgS + 200 kJ

a)

exothermic; energy is written on the product side

b)

endothermic; energy is written on the reactant side.

c)

exothermic; energy is written on the reactant side

d)

endothermic; energy is written on the product side.

86.

If it takes more energy to make bonds than break bonds the reaction is which of the following?

a)

Exothermic

b)

Endothermic

87.

If it takes more energy to break bonds than to make bonds the reaction is said to be which of the following?

a)

Endothermic

b)

Exotermic

88.

If energy is on the reactant side of a chemical equation, the reaction is which of the following?

a)

endothermic

b)

exothermic

89.
A bottle with with water has a mass of 75 grams. A balloon with alka-seltzer has a mass of 5 grams. When the balloon is attached to the bottle and the reaction occurs, what will the total mass be?
a)
The total mass will be 80 grams.
b)
The total mass will be 75 grams.
c)
The total mass will be 70 grams.
d)
The total mass will be 85 grams.
90.

List four factors that affects the rate of a reaction

a)

temperature

b)

concentration

c)

surface area

d)

volume

e)

catalysts

91.

A temperature increase causes the particles ......

a)

to slow down

b)

move faster

c)

collide higher

d)

in the right order

92.

Why does a higher concentration increase the rate of reaction?

a)

it increases the amount of reactants

b)

it lowers the activation energy

c)

it increases the energy of particle collisions

d)

it increases the frequency of particle collisions

93.

Why does a higher temperature increase the rate of a reaction?

a)

it increases both the frequency and energy of particle collisions

b)

it only increases the frequency of particle collisions

c)

it only increases the energy of particle collisions

d)

it reduces the activation energy of the reaction

94.
Why don't all collisions between particles cause a reaction?
a)
the particles also need to collide with a catalyst
b)
not all the particles collide with enough energy
c)
not all the particles collide at a high enough temperature
d)
the particles need to collide with each other twice
95.
What is the rate of reaction?
a)
How fast a reaction is 
b)
How big a reaction is
c)
How loud a reaction is
d)
How much gas a reaction produces
96.

The minimum amount of energy needed for colliding particles to react is called

a)

Chemical Energy

b)

Kinetic Energy

c)

Activation Energy

d)

Potential Energy

97.
Grinding a seltzer tablet into powder increases the rate of reaction due to increased
a)
concentration
b)
surface area
c)
temperature
d)
reactants
98.
How many F atoms are in this compound?
6MgF2 
a)
2
b)
6
c)
8
d)
12
99.
In any chemical reaction, the mass of the products is always:
a)
slightly less than the mass of the reactants
b)
much less than the mass of the reactants
c)
the same as the mass of the reactants
d)
greater than the mass of the reactants
100.
Which is the name of the kind of solid substance formed in this figure?  
a)
aqueous 
b)
precipitate
c)
acid
d)
synthesis 

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