Chem vocab 12/8

solution

A homogeneous mixture of two or more dissolved substances.

Molarity

The concentration of a solution calculated by moles/liters. Increased concentration indicates that there are more moles of the solute dissolved in the solution.

dillution

The process of adding water to a solution, which increases volume and decreases concentration.

reaction rate

 How quickly a reaction proceeds from reactants to products. 

Activation Energy

The minimum energy required to start a chemical reaction.

Collision theory

States that particles must collide with sufficient energy and orientation in order to make or break chemical bonds. It also states that increasing energy or improving orientation will increase collisions and therefore the overall rate of the reaction.

catalyst

Any chemical species that lowers the activation energy of a reaction. This chemical is not actually part of the reaction and therefore is not consumed during the reaction. 

kinetic molecular theory

States that all matter is composed of particles that are in constant, random motion.

kinetic energy

The energy associated with the movement of particles. Equal to 1/2mv².

system

Any chemicals, reactions, or energy transfers that are being studied. 

surroundings

Everything outside of the system that is not being studied. I.e. the rest of the universe.

Heat

The amount of energy that is being transferred between the system and its surroundings.

bond energy

The amount of energy required to break apart 1 mole of a substance. 

enthalpy

The energy difference between reactants and products. Represented by ΔH°

endothermic

When the energy that is required to break chemical bonds in a reaction is greater than the energy released in forming new bonds. +ΔH

exothermic

When the energy that is released when forming new bonds in a reaction is greater than the energy required to break the original bonds. -ΔH°

dynamic equilibrium

The concept that reactions never really stop. Products are constantly being turned into reactants and reactants are being turned back into products. Equilibrium is achieved when concentrations or pressures remain constant.

equilibrium constant

A mathematical relationship between the concentration or pressure of the products and reactants. The magnitude of K indicates favorability of the overall reaction.

reactant favored

Reactions in which the reactants are predominantly present over the products. I.e. very few products are made. K < 1

product favored

 Reactions in which the products are predominantly present over the reactants. I.e. very few reactants left over. K > 1

Le Chatelier’s Principle

States that reactions will always reach equilibrium, even when acted upon by a change. Reactions will “shift” to either form more products or form more reactants in order to reach a new equilibrium.