Science - Chapter 5 - Chemical Reactions

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Every chemical reaction involves a change in:
mass
energy
concentration
state

energy

A reaction that absorbs energy in the form of heat is described as
endothermic
exothermic
combustion
unbalanced

endothermic

In a chemical reaction
there is no change in energy
energy is always absorbed
energy is always released
energy is either absorbed or released

energy is either absorbed or released

Water vapor in the air turns to liquid water in the form of rain. This is an example of a
physical change
chemical change
chemical equation
chemical formula

physical change

A reaction that releases energy in the form of heat:
endothermic
exothermic
combustion
unbalanced

exothermic

A solid that forms from solution during a chemical reaction is called a:
reactant
bond
chemical
precipitate

precipitate

The principle of _______________ states that during a chemical reaction, matter is not created or destroyed

conservation of mass

When two or more substances combine to make a more complex compound, the process is called a:
decomposition reaction
replacement reaction
precipitate reaction
synthesis reaction

synthesis reaction

The minimum amount of energy needed to start a chemical reaction:
exothermic energy
endothermic energy
activation energy
chemical energy

activation energy

A material that increases the rate of a chemical reaction by lowering the activation energy:
catalyst
fuel
chemical energy
activation energy

catalyst

The _________________ is the amount of one material present in a given amount of another material

concentration

A material that decreases the rate of a reaction:
inhibitor
catalyst
enzyme
fuel

inhibitor

Chemicals that act as biological catalysts by speeding up reactions in living things:
inhibitors
enzymes
fules
reactants

enzymes

A __________ is a material that releases energy when it burns.

fuel

Sulfur dioxide, oxygen, and water combine to produce sulfuric acid. This chemical reaction is:
an example of combustion
a synthesis reaction
a replacement reaction
a decomposition reaction

a synthesis reaction

Rust forms when iron metal combines with oxygen in the air to produce Oxide. This reaction is an example of a(n):
chemical reaction
chemical bond
synthesis reaction
activation energy

synthesis reaction

Water vapor in the air turns to liquid water in the form of rain. This is an example of a
physical change
chemical change
chemical equation
chemical formula

physical change

What happens when chemical bonds break and new bonds form?
a physical change
a chemical reaction
matter is destroyed
surface area increases

a chemical reaction

The only sure evidence of a chemical reaction is:
the formation of a gas
a color change
the production of new materials
changes in properties

the production of new materials

Symbols of elements are used to write the formulas of compounds much like:
numbers are used to write coefficients
products are used to make reactants
letters are used to write words
number are used to balance equations

letters are used to write words

In chemical reactions, what does the principle of conservation of mass mean?
Matter is not created or destroyed
The total mass of the reactants is greater than the total mass of products;
the total mass of the reactants is less than the total mass of the products;
Matter is not changed

Matter is not created or destroyed

In an equation, numbers often appear in front of a chemical formula. These number tell you the:
Number of atoms in each molecule in the reaction;
Number of elements in the reaction;
Number of molecules or atoms of each substance in the reaction;
Number of molecules in each atom in the reaction.

Number of molecules or atoms of each substance in the reaction;

A bottle of hydrogen peroxide that eventually turns into a bottle of water and oxygen gas is an example of a:
a synthesis reaction
decomposition reaction
replacement reaction
precipitate reaction

decomposition reaction

The chemical reaction between copper oxide and carbon that produces copper and carbon dioxide is an example of
synthesis
decomposition
precipitation
replacement

replacement

Atoms are held together by forces known as a _________________

chemical bond

A precipitate is a(n) __________ that forms from solution during a chemical reaction

solid

A subscript shows the number of ________ of an element in a molecule

atoms

In a _____________ reaction, the products are simpler substances than the reactant

decomposition

A gas necessary for combustion to take place is ____________.

oxygen

Hydrogen gas and oxygen gas can explode in a violent, exothermic reaction if ignited by a spark. The spark supplies the ___________ for the reaction.

energy

The force that holds atoms together is called:
a chemical bond
conservation of matter
heat
a chemical change

a chemical bond

A shorter, easier way to show chemical reactions, using symbols instead of words, is called a:
chemical equation
chemical formula
symbol
subscript

chemical equation

The substances listed on the left side of a chemical equation are the:
products
coefficients
precipitates
reactants

reactants

Which of the following does NOT increase the number of particles of a substance available to react in a chemical reaction?
increasing the concentration
increasing the surface area
adding a catalyst
increasing the mass

adding a catalyst

Which of these is NOT one of the three things necessary to start and maintain a fire?
fuel
oxygen
carbon dioxide
heat

carbon dioxide

A rapid reaction between oxygen and a fuel is known as:
combustion
heat
activation
decomposition

combustion

In what way can a fire be brought under control?
Add fuel
Add oxygen
Remove oxygen
Remove carbon dioxide

remove oxygen

Water affects most fires by:
cooling the fire and preventing contact between oxygen and fuel;
decreasing activation energy;
producing carbon dioxide and removing fuel;
increasing the temperature

cooling the fire and preventing contact between oxygen and fuel;

What is the best form of fire safety?
a water hose
an extinguisher
the fire department
fire prevention

fire prevention

T/F - In a chemical reaction, the total mass of the reactants is GREATER THAN the total mass of the products.

F - less than

T/F - A change that produces a new substance is a CHEMICAL change.

T

T/F - In a chemical reaction, chemical BONDS are formed or broken

T

T/F - A chemical reaction can be identified by observing changes in the PROPERTIES of matter.

T

T/F - The materials presented at the beginning of a chemical reactIon are called PRODUCTS.

F - Precipitates

T/F - The amount of matter in a chemical reaction CHANGES

F - Stays the same

T/F - SYNTHESIS is the process of making a more complex compound from simpler substances

T

The formation of a gas or a precipitate may be evidence for a(n) _____________________

chemical reaction

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