Module 19 Chemical Reactions

chemical reaction

a change in which one or more substances are converted into new substances

reactants

the substances present at the beginning of the reation

products

the new substances produced in a reaction

chemical equation

a way to describe a chemical reaction using chemical formulas and other symbols

coefficient

the number in front of the formulas in the chemical equations, represent the number of units of each substance taking part in a chemical reaction

balanced chemical equation

an equation that has the same number of atoms of each element on both sides of the arrow

mole

the amount of a substance that contains 6.02 x 10^23 particles of that substance

molar mass

the mass in grams of one mole of a substance

combustion reaction

reaction that occurs when a substance reacts with oxygen to produce energy in the form of heat and light

synthesis reaction

reaction where two or more substances combine to form another substance

decomposition reaction

reaction where one substance breaks down into two or more substances

single-displacement reaction

a reaction where one element replaces another element in a compound

double-displacement reaction

reaction where the positive ion of one compound replaces the positive ion of the other, forming two new compounds

precipitate

an insoluble compound that comes out of a solution during a double-displacement reaction

oxidation

the loss of electrons

reduction

the gain of electrons

exergonic reaction

chemical reaction that releases energy

exothermic reaction

type of exergonic reaction that releases energy in the form of thermal energy

endergonic reaction

chemical reactions that absorb energy

endothermic reaction

type of endergonic reaction that uses thermal energy to keep the reaction going

reation rate

the rate at which reactants change into products

collision model

idea that atoms, ions, and molecules must collide in order to react

catalyst

a substance that speeds up a chemical reaction without being permanently changed itself

inhibitor

a substance that slows down, or prevents, a chemical reaction without being permanently changed itself

reversible reaction

a chemical reaction that can occur in both forward and reverse directions

equilibrium

a state in which forward and reverse reactions or processes proceed at equal rates

Le Chatelier's principle

principle that states that if a stress is applied to a system at equilibrium, the equilibrium shifts in the direction that opposed the stress