electrochemistry?(o2-o3-o9)

According to wikipedia.org, electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solutions at the interface of an electron conductor (a metal or a semiconductor) and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution. In short, electrochemistry is the branch of chemistry that deals with the relationship between electricity (flow of electrons) and chemical reactions (http://bouman.chem.georgetown.edu/S02/lect25/lect25.htm).

If a chemical reaction is driven by an external applied voltage, as in electrolysis, or if a voltage is created by a chemical reaction as in a battery, it is an electrochemical reaction. Chemical reactions where electrons are transferred between molecules are called oxidation/reduction (redox) reactions. In general, electrochemistry deals with situations where oxidation and reduction reactions are separated in space or time, connected by an external electric circuit to understand each process(wikipedia.org).

Oxidation is defined as the interaction between oxygen molecules and all the different substances they may contact, from metal to living tissue. Technically, however, with the discovery of electrons, oxidation came to be more precisely defined as the loss of at least one electron when two or more substances interact. Those substances may or may not include oxygen. While, reduction is the gain of electrons or the addition of at least one electron when substances come into contact with each other. (http://www.wisegeek.com/what-is-oxidation.htm)

RULES:

1. The oxidation # of free element is 0.
2. The oxidation # of ions = charge.
3. the oxidation # of -2 except peroxide (O2)(-1)
4. the oxidation # of H ion is always +1 except metallic hydride (-1)
5. the sum of the charges in a compound = 0
6. the algebraic sum of oxidation # of poly ions = charges

Identifying oxidizing and reducing agents in redox reactions

1. Assign oxidation numbers (follow the rules above).

2. After you have assigned oxidation numbers, identify the elements whose oxidation numbers have changed.

3. The reactions that we will study for this topic this semester are already balanced. Sometimes, reactions will be given as half reactions, for this particular instance, what is necessary is to balance the number of electrons before combining the two half reactions.