Glencoe Chemistry Chapter 15 Quiz #2

spontaneous

changes in enthalpy and entropy determine whether a process is

spontaneous process

any physical or chemical change that has occurred with no outside intervention

rust on iron, exothermic & increase in entropy

entropy (S)

is a measure of the number of possible ways that the energy of a system can be distributed or the randomness of the particles within that system.

second law of thermodynamics/ law of disorder

What Law: spontaneous process always proceed in such a way that the entropy of the universe increases

nonspontaneous process

endothermic

rust will not decompose spontaneously into iron and oxygen under ordinary conditions

system

the particular reaction or process being studied

change in entropy equation

∆S system = S products - S reactants

∆S systems is positive if S products __ S reactants

S products > S reactants

means positive

converse is true

(entropy increases)

∆S systems > 0 (positive) if

substance changes from

solid to liquid

and liquid to gas

in liquids and gas molecules can move more freely (more entropy) than solids

(entropy decreases)

∆S systems < 0 (negative) if

gas is dissolve in a solvent (liquid or solid)

more entropy when can move freely than when limited by a liquid or solid

(entropy increases)

∆S systems > 0 (positive) if

assuming no change in physical state occurs,

the entropy of a system increases when

the number of gaseous product particles is greater than the number of gaseous reactant particles

(entropy increases)

∆S systems > 0 (positive) if

when a solid or a liquid dissolves in a solvent

(entropy increases)

∆S systems > 0 (positive) if

as temp increases

Gibbs free energy (G system)

energy that is available to do work

∆G system =

∆H - T ∆S

∆H is change in enthalpy

T is temp

∆S is change in entropy

free energy released or absorbed ina chemical reaction is equal to

the difference between the enthalpy change

and the product of change in entropy (in joules per kelvin)

and the temp (in kelvins)

if free energy change is negative the reation is

spontaneous