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Avogrados number

6.022x10²³; 1 mole = 6.022x10²³

Limiting reactant

limits the extent of the reaction deterining the amount of product formed

excess reactant

reactants left over when a reaction stops

theoretical yied

maximum amount of product that can be produced from a given amount of reactant

actual yeal

amount of product produced when the chemical reaction is carried out in an experiment

kinetic molecular theory

the theory that all matter is composed of particles (atoms and molecules) moving constantly in random directions

unit cell

smallest arrangement of atoms in a crystal lattice that has the same symmetry as the whole crystal

crystalline solids

solid whose atoms ions and molecules are arranged in an orderly geometric structure

surface tension

energy required to overcome the attrations holding the surface particles in the interiro thus increasing the surface are of the liquid

melting point

the temperature at which the forces holding a crystal lattice together are broken and it becomes a liquid

evaporation

when vaporization occurs only at the surface of the liquid

vapor pressure

the pressure exerted by a vapor over a liquid

boiling point

the tem at which the vapor pressure of a liquid equals the external pressure

sublimation

ability to change directly form the solid phase to the gas phase

condensation

when watervaport molecules lose energy, its velocity decreases making them more likely to form hydrogen bonds with another water molecule

freezing point

a temperature at whcih a liquid is converted into a crystalline solid

deposition

process by which a ubstance changes froma gas or vaport to a solid w/o first becoming a liquid

avogrados principle

equal volumes of fases at the same temp and pressure contain equal numbers of particles

triple point

represents the temperature and ressure at which 3 phases of a substance can coexist

critical point

indicates the critical pressure and temp above which water can;t exist as a liquid

boiling point elevation

the difference in temperature between the boiling point of a solution and the boiling point of the pure solvent

freezing point depression

the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent

law of conservation of energy

the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes

chemical potential energy

energy stored in a substance bc of its composition

energy

ability to do work or produceheat

potential energy

energy due to the position of a object

heat

energy in the profess of flowing from a warmer oject to a cooler object

calorie

the amtof energy required to raise the temp of 1g of ure water by 1c

joule

si unit of energy and heat

specific heat

amt of heat required to raise the temp of 1g fof that substance by 1C

exothermic

heat flows from the system to the surroundings (-) lose heat-right, negative

thermochemistry

study of heat changes that accompany chemical reactions and phase changes

endothermic

heat flows from the surrounding to the system (+) gain heat-left, positive

enthalpy

the heat content of a system at constant pressure

enthalpy heat reaction

the change in enthalpy for a reaction

hess's law

the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process

standard state of a substance

normal phusical state of the substance at 1 atm

standard enthalpy heat of formation

The change in enthalpy that accompanies the formation of one mole of a compound in its standard state from its constituent elements in their standard states.

thermochemical equation

a balanced equation that includes the physical stateof all reactants and products and the enegry change

enthalpy of combustion of a substance

the enthalpy change for the complete burning of one mole of the substance

molar enthalpy of vaporization

the amount of energy as heat that is needed to vaporize one mole of liquid at the liquid's boiling point

molar enthalpy of fusion

the amount of energy as heat required to chang 1 mol of a substance from solid to liquid at constant temperature and pressure

molar enthalpy of condensation

= the molar enthalpy (heat) of vaporization (same numerical value) but opposite signs!

molar enthalpy of solidification

= molar enthalpy (heat) of fusion (same numerical value) but opposite signs!

reversible reaction

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

chemical equilibrium

in a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction.

law of chemical equilibrium

states that at a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value

equilibrium constant

the ratio of product concentrations to the reactant concentrations at equilibrium, with each concentration raised to the power equal to the number of moles of that substance in a balanced chemical equation; Keq.

equilibrium constant expression

Keq= [products]/[reactants]

homogeneous equilibrium

all reacting species are in the same phase

heterogeneous equilibrium

equilibrium involving reactants and/or products in more than one phase

le chateliers principle

States that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.

stress

any kind of change in a system at equilibrium, the system shifts in the direction that relieves the stress

boyles law

The relationship between the pressure and volume of a gas at constant temperture; when volume increase, pressure decreases.

catalyst

speeds up the reaction

shifts to right

adda reactant, remove a product lower the tempreature in an exothermic reaction, raise the temperature in an endothermic reaction

shifts to the left

remove a rectant remove a product raise the temperature in an endothermic reaction, lower the temperature in an exothermic reaction

arrhenius model

An acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution; A base is a substance that contains a hydroxide group and dissociates to produce a hydroxide ion in aqueous solution

bronsted lowry

Acids are proton donors - give off H+, bases are proton acceptors - take in H+

conjucate acid

species produced when a base accepts a hydrogen ion

conjugate base

the species produced when an acid donates a hydrogen ion to a base

strong acid

acids that ionize completely

weak acid

acids that ionize partially

strong base

base that dissociates entirely into metal and hydroxide ions

weak base

base that ionizes only partially in dilute solution

Ph

-log[h+]

pOH

-log[oh-]

acidic solutions

pH below 7, pOH above 7

basic solutions

pH above 7, pOH below 7

neutralization reaction

a chemical reaction in which an acid and a base interact with the formation of a salt

titration

a measured amount of a solution of unknown concentration is added to a known volume of a second solution until the reaction between them is just complete

equivalence point

The point during a titration when the number of H+ ions and OH- ions are equal. This is at the middle of the steepest part of the titration curve.

end point

the point in a titration at which a marked color change takes place

redox reaction

A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.

oxidation

The loss of electrons from a substance involved in a redox reaction.

reduction

the gain of electrons by atoms of a substance

reducing agent

a substance capable of bringing about the reduction of another substance as it itself is oxidized

oxidizing agent

the substance that oxifizes another substance by accepting its electrons

oxidation number

positive or negative number that indicates how many electrons an atom has gained, lost, or shared to become stable

electrochemical cell

an apparatus that uses a redox reaction to produce electrical energy or uses electrical energy to cause a chemical reaction

electrodes

an electrically conductive material, usually a metallic strip that conducts electrons into and out of the solution in a half cell

anode

the electrode where oxidation takes place

cathode

the electrode where reduction takes place

cell potential

the difference between the reduction potentials of two half-cells

reduction potential

a measure of the tendency of a given half-reaction to occur as a reduction in an electrochemical cell

salt bridge

A tube that allows the slow transfer of ions and maintains the neutrality of the electrolyte solutions.

electrolytic cell

a cell in which the flow of electrical energy from an external source causes a redox reaction to occur

electrolysis

the use of electrical energy to bring about a chemical reaction

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