Chap 14 - Electrochemical Cells

Voltaic Cell

AN arrangement of 2 half-cells, separated by a porous boundary, that spontaneously converts chemical energy to electrical energy.

Electrolytic cell

A cell in which a non-spontaneous reaction is forced to occur; a combination of 2 electrodes, an electrolyte, and an external power source.

Cathode

electrode where reduction occurs

Anode

electrode where oxidation occurs

what direction do ions flow?

• cations towards cathode

• Anions towards anode

electrolysis

• process of supplying electrical energy to force a nonspontaneous redox reaction to occur.

electroplating

process of depositing a metal onto another object that is the cathode of a cell.

secondary cell

• A rechargeable cell

• example is phone & car batteries

corrosion

An electrochemical process in which a metal reacts with a substance in the environment, returning the metal to an ore-like state

Standard cell potentials

• the maximum electrical potential difference (voltage) of the cell operating under standard conditions

• energy difference (per unit of charge) between cathode and anode

Inert electrodes

An unreactive solid conductor in a cell that provides a location to connect a wire and a surface on which a half-reaction may occur.

Why do we need a saltbridge / porous boundary?

So balance may be maintained between the 2 half-reactions.

Half-cell

AN electrode-electrolyte combination forming one-half of a complete cell.

Fuel-cell

An electric cell that produces electricity by the reaction of a fuel that is continuously supplied to keep the cell operating.

Electric current

• A measure of the rate of flow of charge past a point in an electrical circuit

• measured by an ammeter in amperes

Electric Potential Difference

Energy difference per unit charge, between any 2 points in an electrical circuit

• measured in volts

Battery

A set of 2 or more electric (or voltaic) cells joined in a series to produce a larger voltage.

standard cell potential of voltaic cell vs. electrolytic

• voltaic (+)

• electrolytic (-)

What are the similarities & differences of voltaic and electrolytic cells?

Similarities

• 2 electrodes

• conductive medium

• vessel

Galvanic

• production of current

• spont.

• saltbridge

• anode (-); cathode(+)

Electrolytic

• needs power source

• non-spont.

• anode (+); cathode (-)

Standard Cell

A voltaic cell in which each half-cell contains all entities shown in the half-reaction equation at SATP conditions, with a concentrations of 1.0 M for the aqueous solutions.

Standard Reduction Potential

The ability of a standard-half cell to attract/gain electrons under standard conditions

cathodic protection

An effective method of preventing corrosion of iron in which the iron is forced to become the cathode by using either an impressed current or a sacrificial anode.

Faradays Law

• mas of an element produced or consumed at an electrode is directly proportional to the time the cell operates, as long as the current is constant or vice versa

• The relationship between a changing magnetic field and an induced electromotive force (emf) in a conductor. The emf is directly proportional to the rate of change of magnetic field and the number of turns in the coil.