Electrochemistry Flashcards
oxidation
loss of electrons
reduction
gain of electrons
what agent is the oxidized atom
reducing agent
what agent is the reduced atom
oxidizing agent
what happens at anode
oxidation
what happens at cathode
reduction
galvanic cell function
flow of electrons create an electric current that can do work in a redox reaction. spontaneous redox reactions generate electric currents
anode
electron source
cathode
electron sink
how do electrons flow in galvanic cell
anode to cathode
salt bridge anion and cation destinations
anion goes to anode, cation goes to cathode
what do salt bridges complete
circuit
what are the standard conditions
25 degrees celcius, 1 atm, 1 M
what is free energy change for a redox reaction?
delta G = -nFE
What must cell voltage and free energy be to be spontaneous
cell voltage positive, free energy negative
If a reduction potential is negative, what are characteristics of reactant
better as a reducing agent, weak oxidizing agent
if a reduction potential is positive, what are characteristics of reactant
stronger as an oxidizing agent and weaker as a reducing agent
What are nonstandard conditions
when solution does not equal 1 M and nernst equation must be used
concentration cell
galvanic cell with identical electrodes but has half cells with different ion concentrations
what is anode in concentration cell
lower concentration solution
what is cathode in concentration cell
higher concentration solution
when does reaction stop in concentration cell
when concentrations are equal
what is standard cell voltage in concentration cell
zero, since ions in two beakers have same identities
redox indicator
uses change in color to determine endpoint. change is due to change in oxidation state
what makes a redox indicator an ideal indicator
having a high redox potential for determination of solution with oxidizable species
At half equivalence point
oxidized and non oxidized are equal and Q = 1. E= E prime
Electrolytic Cells
Use external voltage (battery) to create electric current that forces nonspontaneous reactions to occur.
Electrolysis
use of electrolytic cells
Electroplating
electrolytic cells are used for plating thin layer of metal on top of another material
Anode in electrolytic cells charge
positive, because electrons are forced to move
Cathode in electrolytic cells charge
negative, because electrons are forced to move
Faraday’s Law of electrolysis
amount of chemical charge is proportional to amount of electricity that flows through cell
Faraday
magnitude of charge on 1 mole of electrons
