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grade 7 change in energy in chemical reaction

Total questions: 124

Worksheet time: 1hrs 10mins

Name
Class
Date
1.
What is required for chemical bonds to break in a chemical reaction?
a)
Heat
b)
Energy
c)
Light
d)
Sound
2.
Which of the following describes a process where energy is absorbed by the reactants?
a)
Exothermic reaction
b)
Endothermic reaction
c)
Exergonic reaction
d)

Endrgonic reaction

3.
How do hot and cold packs work in terms of energy?
a)
Both absorb energy
b)
Hot packs release energy, cold packs absorb energy
c)
Hot packs absorb energy, cold packs release energy
d)
Both release energy
4.
Which energy change occurs when bonds are formed between atoms?
a)
Energy is absorbed
b)
Energy is released
c)
Energy is neither absorbed nor released
d)
Energy is stored in the bond
5.
What determines whether a chemical reaction is endothermic or exothermic?
a)
The type of chemical bonds involved
b)
The energy required to break bonds and the energy released when bonds are formed
c)
The temperature of the surroundings
d)
The concentration of reactants
6.
Which statement about energy in chemical reactions is correct?
a)
Energy is created
b)
Energy is conserved
c)
Energy is released
d)
Energy is transferred
7.
What happens to the energy in an exothermic reaction?
a)
Energy is absorbed from the surroundings
b)
Energy is released to the surroundings
c)
Energy is conserved
d)
Energy is transferred
8.
Why is energy needed to break chemical bonds?
a)
To form new bonds
b)
To overcome the attraction between atoms
c)
No energy change
d)
Energy is stored
9.
What happens in an exothermic reaction when the products form?
a)
Energy is absorbed
b)
Energy is released to the surroundings
c)
No energy change
d)
Energy remains unchanged
10.
What happens to energy in a chemical reaction?
a)
Energy is conserved
b)
Energy is created
c)
Energy is transferred
d)
Energy is absorbed
11.
How is energy released in exothermic reactions?
a)
Energy is released
b)
Energy is absorbed
c)
Energy is conserved
d)
Energy is not absorbed
12.
How does energy transfer occur in endothermic reactions?
a)
Energy is released to the surroundings
b)
Energy must be constantly absorbed
c)
Energy is released
d)
Energy is neither absorbed nor released
13.
What happens when energy is transferred from a hot pack?
a)
Light
b)
Energy is released
c)
Energy is stored
d)
Energy is neither absorbed nor released
14.
What is released during the chemical reaction in fireworks?
a)
Increases collision frequency
b)
Thermal energy
c)
Energy remains unchanged
d)
Heat and light
15.
What is the result of increasing the concentration of reactants in a reaction?
a)
Releases energy
b)
Increases collision frequency
c)
No energy change
d)
Increases the rate of reaction
16.
What can affect the rate of a chemical reaction?
a)
Increased concentration leads to higher reaction rates
b)
Energy is stored
c)
More energy is required to break bonds
d)
Energy is absorbed from surroundings
17.
What happens during cellular respiration?
a)
Energy is stored
b)
Light
c)

Energy is released

d)
More energy is needed
18.
How does concentration affect the rate of reaction?
a)
Higher concentration increases rate
b)
Lower concentration increases rate
c)
Temperature has no effect
d)
Concentration has no effect
19.
What is a crucial feature of an exothermic reaction?
a)
Energy is absorbed from the surroundings
b)
Energy is released to the surroundings
c)
Energy remains constant
d)
Energy is not transferred
20.
What happens when energy is absorbed in a reaction?
a)
Energy is absorbed by the system
b)
Energy is released by the system
c)
No energy transfer occurs
d)
Energy is conserved
21.

Which of the following is true about energy changes in a chemical reaction?

a)

Energy can be transformed

b)

Energy is created

c)

Energy is only absorbed

d)

Energy is always lost

22.

What role does activation energy play in chemical reactions?

a)

It is the energy required to start a reaction

b)

It is the energy released during a reaction

c)

It is the energy stored in products

d)

It has no effect on the reaction

23.
_______________ is an example of both a color change and new substance produced from a chemical change with oxygen and metal.
a)
shredded paper
b)
rust (iron oxide)
c)
wood chips
d)
melted wax
24.
A candle wick burning is an example of a _________________________
a)
physical reaction
b)
condensation
c)
neutrons
d)
chemical reaction
25.
In a ___________change, a substance changes into a different substance.
a)

Physical

b)

Chemical

c)

Energy transfer

d)

exothemic

26.
Which of these is NOT a sign that a chemical change has occurred? 
a)
Change in shape.
b)
An unexpected color change
c)
A temperature change
d)
The formation of a precipitate
27.

You know that a chemical reaction has occurred if

a)

there is a precipitate (new solid)

b)

there is a color change.

c)

there is a temperature change.

d)

All of these answers are evidence.

28.
When a candle melts, it is a ___________________  change.
a)
chemical
b)
physical
c)
transparent
d)
undefined
29.
What indicates a chemical reaction occurred?
a)
Heat or Light is released
heat or light is produced
b)
gas (bubbles) produced
c)
color change
d)
all of the above
30.

A(an) ______ is the number that appears before a formula in a chemical equation.

a)

subscript

b)

coefficient

c)

ratio

d)

denominator

31.

How is a chemical change different from a physical change?

a)

there is no difference

b)

a physical change creates a new substance

c)

a chemical change creates a new substance

d)

energy is released when atoms form bonds.

32.

Which of the following IS a physical change?

a)

Getting a haircut

b)

Rusty metal

c)

A compound

d)

sour milk

33.

A chemical change is different than a physical change because in a chemical change

a)

chemicals are used

b)

molecules do not physically touch

c)

a new substance is formed and in a physical no new substance is formed

d)

the change can be seen but in a physical change it cannot

34.
the starting materials in a chemical reaction
a)
Products
b)
Reactants
c)
Starters
d)
Enders
35.

In chemical reactions, what does the Law of Conservation of Matter 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.

36.
The substances listed on the right side of a chemical equation are the
a)
Yields
b)
Reactants
c)
Products
d)
Precipitates
37.
The blue numbers in the image below represent ________
a)

reactants

b)

coefficients

c)

subscripts

d)

none of the answers are correct

38.

What is the total energy possessed within an object or system due to the movement of the particles within the object or system?

a)

Potential energy

b)

Thermal energy

c)

Temperature

39.

What is the measure of the average kinetic energy of the particles within an object or system?

a)

Temperature

b)

Thermal energy

c)

Speed

d)

Kinetic unit

40.

True or False: Chemical reactions either consume thermal energy or produce it, depending on the chemicals involved.

a)

True

b)

False

41.

Making chemical bonds ____________ energy in the form of heat and light.

a)

absorbs

b)

creates

c)

releases

d)

destroys

42.

Breaking chemical bonds requires __________ of heat energy to complete the work.

a)

release

b)

the creation

c)

the destruction

d)

absorption

43.

Chemical reactions that release thermal energy into the surroundings are called

a)

exothermic reactions.

b)

endothermic reactions.

c)

heat reactions.

d)

cold reactions.

44.

During an exothermic reaction, you will observe

a)

a decrease in temperature.

b)

an increase in temperature.

c)

no change in temperature.

45.

Chemical reactions that absorb thermal energy from the surroundings are called

a)

exothermic reactions.

b)

endothermic reactions.

c)

heat reactions.

d)

cold reactions.

46.

During an endothermic reaction, you will observe

a)

a decrease in temperature.

b)

an increase in temperature.

c)

no change in temperature.

47.

Photosynthesis is an example of

a)

an exothermic reaction.

b)

an endothermic reaction.

48.

Combustion is an example of

a)

an exothermic reaction.

b)

an endothermic reaction.

49.

For an endothermic reaction

a)

the starting energy of the reactants is greater than the ending energy of the products.

b)

the starting energy of the reactants is less than the ending energy of the products.

c)

there is no change in energy between reactants and products.

50.

For an exothermic reaction

a)

the starting energy of the reactants is greater than the ending energy of the products.

b)

the starting energy of the reactants is less than the ending energy of the products.

c)

there is no change in energy between reactants and products.

51.

True or False: Because of the energy difference between making and breaking bonds, chemical reactions almost always involve a change in energy from start to finish.

a)

True

b)

False

52.

Cooking is an example of an

a)

exothermic reaction.

b)

endothermic reaction.

53.

Rusting is an example of an

a)

exothermic reaction.

b)

endothermic reaction.

54.

An instant hot pack is an example of an

a)

exothermic reaction.

b)

endothermic reaction.

55.

An instant cold pack is an example of an

a)

exothermic reaction.

b)

endothermic reaction.

56.

Respiration is an example of an

a)

exothermic reaction.

b)

endothermic reaction.

57.

What happens to particles when their temperature increases?

a)

The particles move slower

b)

The particles move faster

c)

The particles lose mass

d)

The particles gain mass

58.

The model shows ice in a particle model. As thermal energy increased, the water particles _________________.

a)

moved apart; increased speed

b)

moved closer; increased speed

c)

moved apart; decreased speed

d)

moved closer; decreased speed

59.

In which state of matter are the molecules spaced farthest apart?

a)

Solid

b)

Liquid

c)

Gas

d)

All are equal

60.

When ice sits out on a counter and melts, it is because the ice has...

a)

gained mass

b)

gained energy

c)

lost mass

d)

lost energy

61.

According to the Law of Conservation of Mass,

a)

matter is always created in a chemical reaction

b)

matter is always destroyed in a chemical reaction

c)

matter is created and then destroyed in a chemical reaction

d)

matter is not created or destroyed in a chemical reaction

62.

Substances created, or made, during a chemical reaction are known as the

a)

reactants

b)

products

c)

chemicals

d)

substances

63.

Substances that start a chemical reaction are known as the

a)

reactants

b)

products

c)

chemicals

d)

substances

64.

The law of conservation of mass can be demonstrated by a chemical reaction. Which of the following models of a chemical reaction best represents the law of conservation of mass?

a)
b)
c)
d)
65.

In which of the following examples has a chemical reaction occurred?

a)

After putting liquid batter into a hot pan, the batter solidifies and begins to turn brown.

b)

After turning on a blender filled with fruits, the fruit is chopped up and mixed together.

c)

After taking a tray filled with ice cubes out of the freezer, the cubes begin to melt.

d)

After adding a spoonful of sugar to a mug of hot coffee, the sugar dissolves completely.

66.

When carbon and oxygen combine chemically, the mass of the product is

a)

greater than the mass of the carbon plus the mass of the oxygen

b)

equal to the mass of the carbon plus the oxygen

c)

equal to the mass of the carbon

d)

less than the mass of the carbon

67.

The picture to the right shows a demonstration of water changing from the liquid phase to the gas phase as it boils in a beaker.Which of the following statements explains why this demonstration cannot be used to prove that matter is conserved during a change of phase?

a)

The change of phase is incomplete.

b)

Water is changing both phase and temperature.

c)

Water in the gas phase is lighter than liquid water.

d)

The change of phase is taking place in an open system.

68.
How many Oxygen are in H2O?
a)
1
b)
2
c)
0
d)
4
69.

How many Nitrogen atoms are in N2?

a)
6
b)
8
c)
2
d)
4
70.

___________________ are materials that ALLOW heat and electricity to move easily through them.

a)

Conductors

b)

Insulators

71.

______________ are materials that RESIST the flow of heat or thermal energy.

a)

Conductors

b)

Insulators

72.
What is a insulator?
a)
a material that slows the transfer of heat
b)
a material that transfers heat easily
c)
a material that is fluffy
d)
a material that is temperature controlled
73.
If a chemical reaction is EXOTHERMIC, the temperature would....
a)
Stay the same
b)
Increase
c)
Decrease
74.

In an endothermic reaction, heat is ...

a)

taken in

b)

given out

75.
In an exothermic reaction, heat is ...
a)
taken in
b)
given out
76.
During an endothermic reaction in a beaker if we are part of the surroundings and touched the beaker, it would feel _______. 
a)
Warm
b)
Cold
77.

Any characteristic of matter that you can observe with out changing the identity of the substances that make it up is a ________ property.

a)

Chemical

b)

Physical

78.

Any characteristic of matter that can be observed as it changes to a different type of matter a ________ property.

a)

Chemical

b)

Physical

79.

What is the property used to identify materials that describes the ability for electricity to flow through a substance called?

a)

flammability

b)

density

c)

solubility

d)

conductivity

80.

What is the property used to identify materials that describes the ability of one material to dissolve in another material called?

a)

flammability

b)

density

c)

solubility

d)

conductivity

81.

What is the property used to identify materials that describes the amount of mass in an object compared to its volume called?

a)

flammability

b)

density

c)

solubility

d)

conductivity

82.

What type of property is the ability of a substance to burn, or flammability?

a)

chemical

b)

physical

83.

What type of property is the ability of a substance to dissolve into another substance, solubility?

a)

chemical

b)

physical

84.

What type of property is the ability of a substance to react with another substance like HCL acid, reactivity?

a)

chemical

b)

physical

85.

What type of property is the ability of a substance to react with oxygen and rust, oxidation?

a)

chemical

b)

physical

86.

What type of property is the ability of a substance conduct electricity through it, conductivity?

a)

chemical

b)

physical

87.

What are the signs that a chemical reaction has occurred?

a)

change in temperature

b)

change in color

c)

bubbles

88.

Two different silver metals were found on the shelf of my science storage room and I need to put them back in the correct spot. They are either aluminum or iron. The metals are different densities, have different melting and boiling points, and iron rusts and aluminum doesn't. What would be best for me to do to identify what metal it is?

a)

boil it in hot water

b)

check to see if it rusts

c)

scratch the surface with a hard tool

d)

weigh it on a balance

89.

What is the law of conservation of mass?

a)

In any chemical reaction, the mass of the products is always greater than the mass of the reactants because some mass is lost during the reaction.

b)

In any chemical reaction, the mass of the products is always less than the mass of the reactants because some mass is added during the reaction.

c)

In any chemical reaction, the mass of the products is always equal to the mass of the reactants because no mass is lost during the reaction.

90.

If I put add an alka seltzer tablet to a glass of water, it produces bubbles. What happens to the mass inside the glass after the reaction?

a)

The mass stays the same.

b)

The mass in the glass increases because when the atoms combine they are heavier than the were in the begining.

c)

The mass in the glass decreases because some of the mass escapes in the bubbles that are created during the reaction.

91.

What model of the energy transfer is occurring in and endothermic reaction?

a)
b)
92.

What model of the energy transfer is occurring in and exothermic reaction?

a)
b)
93.

The following chemical reaction occurred during the experiment in the picture.

Citric acid + Sodium bicarbonate -> Carbon dioxide + water + Sodium citrate


What happens to the total mass before and after the reaction?

a)

The mass increases.

b)

The mass decreases.

c)

The mass stays the same.

94.

The following chemical reaction occurred during the experiment in the picture.

Citric acid + Sodium bicarbonate -> Carbon dioxide + water + Sodium citrate

What happened to the temperature during the reaction?

a)

it decreased

b)

it increased

95.

The following chemical reaction occurred during the experiment in the picture.

Citric acid + Sodium bicarbonate -> Carbon dioxide + water + Sodium citrate


During the reaction, the bottle became colder. What model of the energy transfer is occurring in this reaction?

a)

endothermic

b)

exothermic

96.

The following chemical reaction occurred during the experiment in the picture.

Citric acid + Sodium bicarbonate -> Carbon dioxide + water + Sodium citrate

What was the direction of energy of the reaction?

a)

energy in

b)

energy out

97.

Eggs being cooked in a skillet is an example of an ____________ reaction because the eggs absorb heat (energy).

a)

endothermic

b)

exothermic

98.

Toothpaste breaks down acids in your mouth which releases energy. This is an example of an ____________ reaction.

a)

endothermic

b)

exothermic

99.

When rust forms on nails, new bonds are formed and energy is released. This is an example of an _____________ reaction.

a)

endothermic

b)

exothermic

100.

Energy is released during the process of cellular respiration. This is an example of an ___________ reaction.

a)

endothermic

b)

exothermic

101.

One of the products of combustion is heat. This means it is an example of an ____________ reaction.

a)

endothermic

b)

exothermic

102.

During evaporation, water absorbs heat so that bonds can break and water vapor forms. This is an example of an _____________ reaction.

a)

endothermic

b)

exothermic

103.

During photosynthesis, plants absorb energy (heat) from the sun to break down the bonds in water and carbon dioxide. This process is an example of an _____________ reaction.

a)

endothermic

b)

exothermic

104.

Lighting a match produces heat (energy) as the match stick burns. This is an example of an ____________ reaction.

a)

endothermic

b)

exothermic

105.

_____ reactions usually feel hot!

a)

endothermic

b)

exothermic

106.

In an endothermic reaction, energy is _________.

a)

absorbed

b)

released

107.

What kind of equation is this: 2KI + MgCl2 + 200KJ ----> 2KCl + MgI2

a)

Endothermic

b)

Exothermic

108.

What term is given to a reaction which transfers heat energy to the surroundings?

a)

Endothermic

b)

Reversible

c)

Exothermic

d)

Exotermic

109.

if more heat energy is released in making bonds in the products than is taken in when breaking bonds in the reactants

a)

Exothermic

b)

Endothermic

c)

Exotermic

d)

Endotermic

110.

if less heat energy is released in making bonds in the products than is taken in when breaking bonds in the reactants

a)

Endothermic

b)

Exotermic

c)

Exothermic

d)

Entrothermic

111.

What type of chemical reaction absorbs energy and requires energy for the reaction to occur?

a)

Endothermic

b)

Exotermic

c)

Exothermic

d)

Endotermic

112.
In an exothermic reaction, heat is ...
a)
taken in
b)
given out
113.

In an endothermic reaction, heat is ...

a)

taken in

b)

given out

114.
During an endothermic reaction in a beaker if we are part of the surroundings and touched the beaker, it would feel _______. 
a)
Warm
b)
Cold
115.
If a chemical reaction is EXOTHERMIC, the temperature would....
a)
Stay the same
b)
Increase
c)
Decrease
116.
What type of reaction is shown in the photo?
a)
Exothermic
b)
Isothermic
c)
Endothermic
d)
None of the  above
117.

_____ reactions usually feel hot!

a)

endothermic

b)

exothermic

118.

____ reactions usually feel cold.

a)

endothermic

b)

exothermic

119.
In an endothermic reaction the system is releasing energy.
a)
True
b)
False
120.

After endothermic and exothermic reactions matter _________________.

a)

stays the same.

b)

is destroyed.

c)

is created.

d)

is denser.

121.
If a chemical reaction is EXOTHERMIC, the temperature would....
a)
Stay the same
b)
Increase
c)
Decrease
122.

In an endothermic reaction, heat is ...

a)

taken in or absorbed

b)

given out or released

c)

Neither

123.

What is an example of exothermic?

a)

firework

b)

ice pack

c)

coal

d)

wood

124.

In an exothermic reaction, heat is ...

a)

taken in or absorbed

b)

given out or released

c)

Neither

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