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