Chem 30 Unit 2 Flashcards
oxidation
LEO. losing electrons; becoming more positive
reduction
gaining electrons; becoming more negative
oxidation, aka…
reducing agent
reduction, aka…
oxidizing agent
when writing half reactions…
always add the electrons to the more positive side
spontaneous reaction
If the OA is higher than the RA
non-spontaneous reaction
If the OA is lower than the RA
redox stoich
find SOA and SRA to build a redox equation
disproportionation reaction
an element/compound undergoes both oxidation and reduction
electrochemical cells
devices that use redox reactions to produce/use electricity
voltaic (galvanic) cells
produce electricity; spontaneous reaction
Has positive voltage value.
Chemical (potential energy) → electrical energy
electrolytic cell
use electricity to drive a reaction; non-spontaneous reaction. Have a negative voltage value (requires minimum value of voltage for reaction to occur). Electrical energy is used to bring about chemical change.
inert electrodes…
do not take part in the reaction
electrodes
are solid. The location where oxidation and reduction occur.
voltmeter
measures differences in electric potential energy. Connected between the wire in voltaic cells.
electrolytic cell wire
a battery is connected
electron flow in electrochemical cells
electrons flow from anode to cathode (alphabetically)
cation/anion flow
Cations flow to the cathode; anions flow to the anode.
in electrolytic cells…
anode is positive, cathode is negative
inert electrode examples…
C, Pt
electrolytic cells…
only utilize one container
molten reactions…
do not include water; cannot calculate voltage using data book
coulomb =
amp x second
chloride exception
when only H2O and Cl- are available for the SRA, the Cl- will be the SRA.
electroplating
use of electrolysis to deposit a thin coating of metal on an object
electroplating metals
the object is made the cathode. The plating metal constitutes the anode of the cell.
corrosion
a spontaneous redox reaction
galvanization
dipping metal in molten zinc
sacrificial anode (cathodic protection)
Technique to protect a metal from corrosion by connecting it to a second metal that is more easily oxidized.
The metal that is to be protected is made the cathode (behaves as an inert electrode)
What cannot be a sacrificial anode?
groups ones
sacrificial anodes…
are materials that are a stronger SRA than the material that you want to protect.
