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88 terms

Chem final martin semester 2

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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