Chemical Reactions

Flashcards for vocabulary related to chemical reactions.

Chemical reaction

Process by which substances collide with enough energy that new bonds are formed between atoms, thus creating new substances.

Reactants

Starting substances in a chemical reaction.

Products

Ending substances in a chemical reaction.

Aqueous

Dissolved in water.

Physical changes

Changes that do not impact a substance’s identity (Ex. state of matter change).

Chemical changes

Changes that result in a new substance from a chemical reaction occurring (Ex. burning).

Collision theory

Reacting particles must collide with enough energy for a chemical reaction to occur.

Signs of a chemical reaction

Release of light or heat, sudden color change, odor change, gas released, formation of a precipitate

Law of Conservation of Mass

Matter cannot be created or destroyed in a system – it can only change forms.

Coefficients

Placed in front of a substance and represent ratios of reactants to products. They are used for balancing reactions and can be changed.

Subscripts

Small numbers within each chemical formula that show the ratio of atoms in a compound. They cannot be changed because changing them changes the identity of the substance.

Oxide

A binary compound with at least 1 atom of oxygen

Salt

A compound made of cations and anions

Electrolysis

The decomposition of a substance by an electric current

Hydrocarbon

A compound made of carbon and hydrogen

Precipitate

An insoluble solid that forms from the ions of two aqueous compounds

Activity series

A list of elements in the order in which they will easily undergo certain chemical reactions

Synthesis Reaction

Two or more reactants combine to form a new compound.

Decomposition Reaction

One reactant breaks down into 2 or more products

Combustion Reaction

When a substance reacts (burns) with O2.

Single Replacement Reaction

One element replaces a like element in a compound.

Double Replacement Reaction

Ions in 2 compounds swap and make 2 new compounds

Chemical equilibrium

A dynamic process where there is no net change occurring in the amount of reactants and products in the system, thus no visible change

Le Chatelier’s Principle

When conditions change for a system at equilibrium, the system responds by reducing the effect of the change

Exothermic

When a reaction releases heat

Endothermic

When a reaction absorbs heat

Equilibrium

The forward and reverse reactions are occurring at the same rate.

Effect of concentration on equilibrium

Adding reactant or removing product favors the forward reaction; adding product or removing reactant favors the reverse.

Effect of temperature on equilibrium

Adding heat to an endothermic reaction or removing heat from an exothermic reaction favors the forward; adding heat to an exothermic reaction or removing heat from an endothermic reaction favors the reverse.

Effect of pressure on equilibrium

Increasing pressure (or decreasing volume) causes a shift to favor whichever direction makes less gas; decreasing pressure (or increasing volume) causes a shift to favor whichever direction makes more gas.

Physical Changes

These do not impact a substance’s identity

Chemical Changes

These result in a new substance from a chemical reaction occurring

Law of Conservation of Mass

The mass of the reactants should equal the mass of the products.

Subscripts

They show the ratio of atoms in a compound.

Coefficients

They represent ratios of reactants to products.

Combustion

Reaction with O2 forming an oxide.

Synthesis

Metal & nonmetal oxides creating salts.

Decomposition

Reactions usually needing heat or electricity to occur.

Double Replacement

Often makes a precipitate, insoluble gas, or molecular compound

Chemical Equilibrium

When the amount of reactants and products do not change.