How does an electrolytic cell differ from a voltaic cell?

Answer 1

A Galvanic cell, or Voltaic cell, named after Luigi Galvani, or Alessandro Volta respectively, is an electrochemical cell that derives electrical energy from chemical reactions taking place within the cell. It generally consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane.

An electrolytic cell decomposes chemical compounds by means of electrical energy, in a process called electrolysis; the Greek word lysis means to break up. The result is that the chemical energy is increased. Important examples of electrolysis are the decomposition of water into hydrogen and oxygen, and bauxite into aluminum and other chemicals.

Answer 2

Both types of cells consist of two electrodes connected to an electrolyte (an ionically conducting phase). Electrode reactions then take place at the electrode-solution surfaces. The change from electronic current to ionic current and visa versa are always accompanied by oxidation/reduction reactions. An electrochemical cell is simply a device that converts chemical energy into electrical energy when a chemical reaction is occurring in a cell. An electrolytic cell converts electrical energy into chemical energy. In an electrochemical cell the reaction occurs spontaneously at the electrodes, while an electrolytic cell reaction is not spontaneous at the electrodes - the reaction has to be forced by applying an external electrical current. In an electrochemical cell the cathode is positive and the anode is negative. In an electrolytic cell the cathode is negative and the anode is positive (does this mean that the electrons are going against their gradient here?). In a spontaneous chemical reaction electrons are passed directly from one element to another. In an electrochemical cell these simultaneous redox reactions are "spatially separated" - i.e. happen at different places. The resultant ions then combine to form a new product. During this process electrons are conducted from the anode to the cathode through an outside electrical current which can be used. This action can be reversed in a electrolytic cell. Electrochemical cells are used usually as batteries, while electrolytic cells are used for electroplating metals. Also, the recharging of a rechargeable battery is an electrolytic reaction.

Answer 3

In an electrolytic cell, electrical energy is used to bring about a non spontaneous reaction.

In a voltaic cell, a spontaneous reaction generates electrical energy.