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