Energy and Chemical Reactions

Energy Changes in Chemical Reactions Tutorial

by David Blankenship

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Fireworks are chemical reactions that release energy. Which of these phenomena are caused by chemical reactions that release energy? If you’re not sure, make a guess.Select all the correct answers.

Fireworks are chemical reactions that release energy. Which of these phenomena are caused by chemical reactions that release energy?

If you’re not sure, make a guess.

• Muscles work to perform a task.

• Fuel burns and heats the surroundings.

• A car's air bag expands by igniting a chemical.

• Plants use sunlight and atmospheric gases to make food.

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Some chemical reactions absorb energy rather than release it. Which of these phenomena are caused by chemical reactions that absorb energy? If you’re not sure, make a guess.

• A battery supplies current to a device.

• A person activates a cold pack by hitting it against a surface.

• A rechargeable battery is plugged in to charge.

• Heat is used to separate a compound into its elements

Multiple Choice

 

a reaction that releases energy

in the form of an electric current

• respiration

• photosynthesis

• electrochemical reaction

• combustion

Multiple Choice

 

a reaction that uses oxygen and

releases heat and light energy

• respiration

• photosynthesis

• electrochemical reaction

• combustion

Multiple Choice

 

a reaction in which plants absorb

energy from the Sun

• respiration

• photosynthesis

• electrochemical reaction

• combustion

Multiple Choice

 

a reaction carried out by cells that

use oxygen and release energy

• respiration

• photosynthesis

• electrochemical reaction

• combustion

Multiple Choice

What has to happen before a reaction takes place?

• Product molecules must collide

• Product molecules must collide with enough power

• Reacting molecules must collide with enough energy

• Molecules must collide with enough power

Multiple Choice

 

energy that a substance has because

of the arrangement of its atoms

• chemical energy

• transition state

• chemical reaction

• activation energy

• temperature

Multiple Choice

Explain how increasing concentrations increases the rate of a reaction

• Less collisions occur

• More movement

• More collisions occur

• Less movement

Multiple Choice

What change in condition increases the speed of the reacting molecules?

• Decreasing temperature

• Increasing temperature

• Decreasing energy

• Increasing power

Multiple Choice

 

A measure of the average kinetic

energy of particles

• chemical energy

• transition state

• chemical reaction

• activation energy

• temperature

Multiple Choice

 

The process of breaking down an

existing set of substances to

form a new set of substances

• chemical energy

• transition state

• chemical reaction

• activation energy

• temperature

Multiple Choice

 

a phase in a reaction in which

existing bonds break to form

new bonds

• chemical energy

• transition state

• chemical reaction

• activation energy

• temperature

Multiple Choice

 

A measure of the average kinetic

energy of particles

• chemical energy

• transition state

• chemical reaction

• activation energy

• temperature

Multiple Choice

 

Energy required to start a reaction

• chemical energy

• transition state

• chemical reaction

• activation energy

• temperature

Multiple Choice

How can you increase the surface area of a solid?

• Divide the solid into smaller pieces

• Get more solid

• Turn it into a gas

Multiple Choice

Which change in condition only affects reactions involving gases?

• Temperature

• Surface area

• Pressure

• Concentration

Multiple Choice

What is the activation energy in a reaction?

• The energy needed for products to be formed

• The energy needed to break products into reactants

• The minimum energy needed to make products

• The minimum energy needed by reactants for them to react

Multiple Choice

What does a catalyst do?

• Speeds up reactants

• Speeds up a chemical reaction

• Speeds up products

• Speeds up particles

Multiple Choice

What do you call a biological catalyst?

• Product

• Reactant

• Biological reaction

• Enzyme

Fill in the Blanks

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Which sentences describe an advantage of using a hydrogen fuel cell instead of burning fossil fuels?

• The reaction of hydrogen and oxygen conveniently takes place inside a fuel cell.

• The combustion reaction of hydrogen and oxygen has a very low efficiency.

• Someday, it may be possible to produce hydrogen fuel using sunlight and water.

• The reaction of hydrogen and oxygen doesn’t create products that negatively affect the environment.