Physical Science: Ch. 12 Review
inhibitor
used to slow the spoilage of food
Which of the following changes is chemical rather than physical?
wood is burned
All chemical reactions occur at the same rate.
False
Chemical equations are balanced by changing the subscripts of the molecules.
False
Exothermic reactions do not require any activation energy.
False
Use the image provided. What has happened to the water in the illustration?
The bonds between the atoms of the water molecule have broken, and instead of water, there is now hydrogen and oxygen.
Geoff observed an experiment in which one compound underwent a chemical reaction that produced two compounds. He classified this is a _____ reaction.
decomposition
Metallic chlorates, when heated, results in metallic chlorides and oxygen. This is a _____ reaction.
decomposition
If two or more substances combine to produce a substance, a ____ reaction has occurred.
synthesis
Sulfur trioxide reacts with water to make sulfuric acid. This is a ____ reaction.
synthesis
A change in ____ is a sign of energy being used in a chemical reaction.
temperature
activation energy
minimum energy to start reaction
If the arrangement of atoms in a substance changes, then which of the following is true?
A chemical reaction has occurred.
Breaking a chemical bond ____ energy.
Absorbs
Why is the law of conservation of mass true?
All atoms at the start of a chemical reaction are present at the end of the reaction.
What does an inhibitor do?
An inhibitor is a substance that slows the formation of a product.
According to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactants?
The masses are always equal.
A chemical reaction is taking place between substance A and substance B. The reaction is taking place in two different containers. Compare the rates of reaction in containers I and II. Explain.
The reaction occurs faster in container II because there is a greater concentration of substance A in that container.
A chemical reaction in which more energy is absorbed than is released is endothermic.
True
Activation energy is the minimum amount of energy needed for a chemical reaction to begin.
True
Energy is needed to break bonds in chemical reactions.
True
When a chemical equation contains the same number of atoms on both sides, the equation is balanced.
True
rate of reaction
a measure of how fast a reaction occurs
Which of the following materials will burn the fastest in open air?
a pile of small splinters made from a two-foot diameter log
Endothermic reactions ____.
absorb more energy than they release
Breaking a chemical bond ____.
absorbs energy from the surroundings
Which of the following is NOT a result of a chemical reaction?
bubbles in boiling water
Chemical reactions ____.
can either release more energy than they absorb or absorb more energy than they release, depending on the reaction
Which of the following is certain proof a chemical reaction has occurred?
change of chemical properties
Atoms rearrange when ____.
chemical bonds break and particles collide with enough energy
_____ is a form of energy contained in chemical bonds.
chemical energy
When a substance combines O(subscript)2 and releases energy, a _____ reaction has occurred.
combustion
Hydrogen peroxide ____ and forms water and oxygen gas.
decomposes
Juanita watched as two compounds reacted and changed into two different compounds. She determined the reaction that she observed was a _______ reaction.
double-replacement
Sodium fluoride and silver nitrate become sodium nitrate and silver chloride. Carbonate and hydrogen ions become water and carbon dioxide. This is a ____ reaction.
double-replacement
chemical change
frying an egg
All substances ____.
have a fixed arrangement of atoms
physical change
ice melting
A(n) ____ slows or stops a chemical reaction.
inhibitor
The _____ switch places in a double-replacement reaction.
negative ions
A catalyst is which of the following?
neither a reactant nor product
An explanation for the law of conservation of matter is that the same _____ is present before and after the reaction.
number of atoms
subscript
number of atoms in a chemical formula
product
present after chemical change
reactant
present before chemical reaction
Each substance written to the right of the arrow in a chemical equation is a ____.
product
conservation of mass
reactant mass equals product mass
endothermic
reaction that absorbs energy
exothermic
reaction that releases energy
Forming a chemical bond ____.
releases energy into the surroundings
An exothermic reaction ____.
releases thermal energy
Kalina conducted an experiment in which she started with one element and one compound and ended up with a different element and a different compound. She classified this a s a _____ reaction.
single-replacement
Zinc combines with hydrochloric acid, the zinc replaces hydrogen. The chemical equation for this reaction looks like the image provided. This is a ____ reaction.
single-replacement
catalyst
speeds up a chemical reaction
enzyme
speeds up reactions in living cells
