Science Chapter 9
minimum energy to start reaction
activation energy
Which type of reaction requires more activation energy?
endothermic
reaction that absorbs energy
endothermic
speeds up reactions in living cells
enzyme
reaction that releases energy
exothermic
All substances _____.
have a fixed arrangement of atoms
A(n) _____ slows or stops a chemical reaction.
inhibitor
used to slow the spoilage of food
inhibitor
The _______________ switch places in a double-replacement reaction.
negative ions
Breaking a chemical bond _____.
absorbs energy from surroundings
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
The French chemist, _______________, conducted experiments that led to the law of conservation of mass.
Antoine Lavoisier
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.
Breaking a chemical bond _______________ energy.
absorbs
Endothermic reactions ______.
absorb more energy than they release
Chemical reactions ______.
can either release more energy than they absorb or absorb more energy than they release, depending on the reaction.
speeds up a chemical reaction
catalyst
Atoms rearrange when _____.
chemical bonds break and particles collide with enough energy
frying an egg
chemical change
_______________ is a form of energy contained in chemical bonds.
chemical energy
When a substance combines with O2 and releases energy, a _______________ reaction has occurred.
combustion
reactant mass equals product mass
conservation of mass
Hydrogen peroxide _______________ and forms water and oxygen gas.
decomposes
Geoff observed an experiment in which one compound underwent a chemical reaction that produced two compounds. He classified this as a _______________ reaction.
decomposition
Metallic chlorates, when heated, results in metallic chlorides and oxygen. This is a _____ reaction.
decomposition
Jaunita 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
An explanation for the law of conservation of matter is that the same _______________ is present before and after the reaction.
number of atoms
ice melting
physical change
Each substance written to the right of the arrow in a chemical equation is a ____.
product
present after chemical reaction
product
a measure of how fast a reaction occurs
rate of reaction
present before chemical reaction
reactant
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 as a _______________ reaction.
single replacement
Zinc combines with hydrochloric acid, the zinc replaces hydrogen. The chemical equation for this reaction looks like: Zn + 2HCl yields ZnCl2 + H2 This is a _____ reaction
single replacement
number of atoms in a chemical formula
subscript
If two or more substances combine to produce one 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
