Gabard 2i. Bil 18/01/18
Voltaic and Electrolytic cells
What are they?
voltaic cell is also
known as a galvanic cell, it was named/ created by Alessandro
Volta (voltaic) and Luigi Galvani (galvanic). It is a type of cell
that makes electrical energy from the chemical reactions that occur
inside itself. The chemical reaction that occur inside of the cell is
a redox reaction. Examples: batteries inside your TV
controller, batteries inside flashlight. Examples of types voltaic
cells: 1-Alkaline cell 2-Daniell cell 3-Simple cell 4-Lead-acid
accumulator 5-Dry cell.
The fact that a voltaic cell can produce energy/ electricity is by
using Zinc (anode) and Copper (cathode) that are connected by a wire
and that are put in a solution: CuSO4. When the wire and
the salt bridge (helps to balance the charges in the galvanic cell,
it is composed of Na+Cl- and 2 cotton plugs
that won’t let the solution of Na+Cl- of
pouring into the cathode and anode sites) are there, they will allow
electrons to move through the wire(s) that connect(s) Cu (with a
strong pull of electrons) to Zn (with a weak pull of electrons) with
a LED between the two. When electrons are in a movement position,
they produce or make electricity which will turn the LED on.
We said that there was two chemical reactions: reduction and
oxidation. The cathode (Cu) part is the site where reduction occurs
and the anode is where the oxidation occurs. That because the
electrons are moving from Zn to Cu and the Zn2+ that are
present on the anode site come across to the cathode site and react
with the Cu2+ to make only Cu ? what happens in the
Copper site is a reduction process:
(aqueous = dissolved in water) + 2e- ? Cu (solid metal)
And in the Zinc site is an oxidation process:Zn
(solid)? Zn2+ (aqueous) + 2e-Now,
these two half cell can be called: the reduction half cell and the
oxidation half cell.
We saw in TP that if you only put 1 Zn and 1 Cu, it won’t provide
enough electricity to turn a LED on. So what we did is we took more
half lemons and connected the 3 Zn and 3 Cu with 4 more wires and it
made the LED turn on with enough electricity that was moving within
the 4 wires.
An electrolytic cell is also happening with redox reaction. It is
where an electric current will make the transfer of the electrons in
the redox reaction.
Difference between a voltaic and electrolytic
salt bridge in the electrolytic cell
Scheme of them both
Electrolytic cell Voltaic cell