Unit 5: Chemical Reactions Vocabulary

Atomic mass unit

A unit of mass to express atomic + molecular weights

Law of conservation of mass

States that the mass of all substances present before a chemical change equals the mass of all the substances remaining after the change

Formula mass

The sum of the atomic weights of the atoms in the empirical formula of the compound

Stoichiometry

The relationship between the relative quantities of substances taking part in a reaction or forming a compound, typically a ratio of whole integers

Base

A substance that produces hydroxide ions (OH-) when dissolved in a water solution

Neutralization

Chemical reaction that occurs when the H3O+ ions from an acid react with the OH- ions from a base to produce water molecules and a salt

Avogadro’s number

The number of atoms/molecules in one mole, equal to 6.023 x 10^23

Endothermic

Chemical reaction that requires thermal energy in order to proceed

Products

In a chemical reaction, the new substance or substances formed

Acid

A substance that produces hydrogen ions in a water solution

Hydronium ion

H3O+ ion, forms when an acid dissolves in water and H+ ions interact with water

pH

A measure of the concentration of the hydronium ions in a solution using a scale ranging from 0 to 14 being the most basic

Chemical equation

Shorthand method used to describe chemical formulas and other symbols

Exothermic

Chemical reaction in which energy is primarily given off in the form of thermal energy

Reactants

In a substance, the substance that reacts

Acid base reaction

A solution that has a high concentration of Hydrogen ions (H+) greater than the concentration of water

Neutral solution

A solution that is neither acidic or basic, it has equal amounts of Hydrogen ions (H+) and Hydroxide (OH-)

Salt

Compound formed when negative ions from an acid combine with positive ions from a base