yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Nanofluidic circuitry wikipedia, lookup

Nanogenerator wikipedia, lookup

Polythiophene wikipedia, lookup

Eo values are given for the left to right direction in equations. Because E o is negative
in the Zn2+| Zn half-cell, the reaction which usually occurs is:
Zn2+(aq) + 2e –
A Gas and its Aqueous Ions
Gas / aqueous ion half-cells require an inert electrode to carry the current in or out of
the half-cell, because gases cannot form conducting electrodes. Platinum Pt, or
carbon C (in the form of graphite), are often used as electrodes.
The half-cell for a gas X2 (g) and its aqueous ions X- (aq) is written as:
X2 (g) , X –(aq)/ inert electrode. (The / is used to separate the conductor from the rest
of the half cell.)
For the chlorine/chloride half-cell, written as,
Cl2 (g), Cl –(aq) / Pt (or C):
 The half-reaction is Cl2 (g) + 2e2Cl-(aq) Eo = +1.36 V
 Cl2(g) is the oxidant
 Cl-(aq) is the reductant
Because Eo is positive in the Cl2, Cl-(aq) half-cell, the reaction which usually occurs
Cl2(g) + 2e2Cl-(aq)
Two Types of Aqueous Ions
Ions can be oxidised and reduced to form other ions, so aqueous ion / aqueous ion
half-cells exist. Ions, like gases cannot form conducting electrodes, so an inert
electrode is used in these half-cells.
The half-cell for the oxidised for of an aqueous ion (M2+(aq)) and the reduced form of
the aqueous ion (M+(aq)) is written as:
M2+(aq), M+(aq) / inert electrode. (The comma is used to separate the two reactants
in the same solution and the / indicates a phase separation between the solution and
the electrode.)
For the iron (III) | iron (II) half-cell, written as
Fe3+(aq), Fe2+(aq) / Pt (or C):
 The half-reaction is Fe3+(aq) + eFe2+(aq)
 Fe (aq) is the oxidant
 Fe2+(aq) is the reductant
Eo = +0.77 V
Because Eo is positive in the Fe3+(aq),Fe2+(aq) half-cell, the reaction that usually
occurs is:
Fe3+(aq) + eFe2+(aq)