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Glossary of Chem 13 exam 3

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change in heat transferred between the system and surroundings
enthalpy
first law of thermodynamics
energy is conserved
reaction that proceeds without outside help
spontaneous process
if spontaneous, the reverse is always
nonspontaneous
most spontaneous reactions are _____ and few are _____
Exo / Endo
q
heat transferred or enthalpy
w
work done
q/T
change in entropy
a reaction in which we can completely restore system and surroundings to their original state
reversible process
extent of randomness in a system
entropy
S
entropy
2nd law of thermodynamics
total entropy of universe increases in any spontanteous process
units for delta S
J/K
heat transferred at constant P
enthalpy or delta H
3rd law of thermodynamics
entropy of a pure substance at absolute zero is zero
the pure substance at 1 atm pressure
standard state
super zero means
in standard state
delta H neg, delta S pos, delta G neg
spontaneous at all temperatures
adding heat _____ entropy
increases
delta H neg, delta S neg, delta G neg
spontaneous at low temperatures
delta H neg, delta S neg, delta G pos
not spontaneous at high temperatures
delta H pos, delta S pos, delta G neg
spontaneous at high temperatures
delta H pos, delta S pos, delta G pos
not spontaneous at low temperatures
delta H pos, delta S neg, delta G pos
never spontaneous
G
gibbs free energy
this process thermodynamically favorable for almost all metals at room temp
oxidation
acidic/basic corrodes iron faster
acidic
protecting a metal from corrosion by making it the cathode in an electrochemical reaction
cathodic protection
metal that is oxidized while protecting the cathode is called the
sacrificial anode
in order to protect a metal, you can attach another metal to it, but the attached metal must have a _____ reduction potential
lower
iron coated with a thin layer of zn
galvanized iron
spontaneous redox reactions occur in
voltaic cells
nonspontaneous redox reactions occur in
electrolytic cells
processes driven by an outside source of electrical energy
electrolysis reactions
in an electrolytic cell, electrons flow from the
anode to cathode
in a voltaic cell, electrons flow from the
anode to cathode
cell EMF for a voltaic cell is
positive
1 W =
1 J/s

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