Electrochem Flashcards
(21 cards)
What is Electrochemistry?
The study of the movement of electrons
Oxi or Redox: if oxidization # increases
Oxidization because we lose electrons (LEO)
Oxi or Redox: when we gain hendryen ions
Reduction because we gain electrons (GER)
What is the reducing agent?
Undergoes oxidization, reduces another substance
What is the oxidizing agent?
Undergoes reduction, oxidizes anther substance
What is the Election Transfer Theory?
The number of electrons lost by oxidization must be equal to the electrons gained by reduction
Where are strong oxidizing agents on the relative strengths table?
On the top left
If you read the table from right to left, which reaction do you see?
Process of oxidization
When is a redox reaction spontaneous?
When OA is physically above RA in the table
When is a redox reaction non-spontaneous?
When OA is physically below the RA on the table
which reaction is placed on the cathode side of the Galvanic and is it positive or negative?
The reduction reaction is placed at the cathode, and it is positive
which reaction is placed on the anode side of the Galvanic and is it positive or negative?
The oxidization reaction is placed at the cathode, and it is negative
Which direction to electrons few in GaIvanic cells?
electron flow from anode to cathode ( - to + )
What does a salt bridge do?
Neutralize change build up by using cations and anions that won’t react with the electrolyte - must be weak oxidizing agents and weak reducing agents (ex - NaCI , KNO3 , LiF )
which comes first in Line Notation? Oxi or Red
Oxidization is always written before Reduction
What is the Standard Hydrogen Electrode?
- A standard electrode to provide a reference point
- potential of this cell is zero volts
- always placed at anode (negative electrode)
- involves hydrogen gas at one atmosphere pressure and 298 K being turned into hydrogen ions
- platinum is needed to provide a surface on which Hydrogen gas can be in contact with the hydrogen ions
Faradays Law - Background info
amount of metal deposited at cathode, depends on # of electrons available to reduce the metal ions to solid
Two ways to increase # of electrons
1) increasing current (I) in amps (A) which flows through the circuit
2) increasing amount of time current flows through circuit
What is Faradays First Law ?
- mass of metal produce at the cathode is directly proportional to the quantity of electricity passed through the cell
- electric charge Q is measured using the unit coulomb Q= I x t
What is Faradays Second Law ?
- when reducing metal ions into solid metal, the number of moles of electrons required equals the charge on the metal ion (ex: Al+3 + 3e- –> Al)
- change associated with one mole of electron - called Faraday
- it is e equal to 96 500 coulomb / 1 mole of e-
Both Laws together (what is the formula)
I x t = ne- x F
