REDOX REACTIONS

Redox reactions are all reactions where the oxidation number changes. Most biological reactions involve a redox reaction.
There are two types of these reactions:


Oxidation is the loss of electrons or an increase in oxidation state by a molecule, ion, or atom
Reduction
is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.

(The oxidation number is a number expressing the nature of the charge of the species in question when formed from the neutral atom)

external image redox.gif


Here are some examples of redox reactions:

1. The reaction between hydrogen and fluorine in which hydrogen is being oxidized and fluorine is being reduced:
H2 + F2 → 2 HF
We can write this overall reaction as two half reactions:
the oxidation reaction: H2 → 2 H+ + 2 e

and the reduction reaction: F2 + 2 e
→ 2 F−

2. Cellular respiration is the oxidation of glucose (C6H12O6) to CO2and the reduction of oxygen to waterThe summary equation for cell respiration is: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O

3. Another example of a redox reaction is a campfire.

4. An important real- life application of oxidation/ reduction reactions is batteries. Batteries use these kinds of reactions to produce and store electric energy, which they can use to power things like golf carts!

5. Rust is an important oxidation reaction.

external image indirect-redox-reaction-experiment.jpeg
Important facts:

Redox reactions occur in single displacement reactions. That means that one element is swapped, like in the example below.


For example, in the reaction between iron and copper sulfate: Fe + CuSO4FeSO4 + Cu
The ionic equation for this reaction is: Fe + Cu2+ → Fe2+ + Cu


external image oxidation-325.jpgexternal image Rust_and_dirt.jpg


Questions:


1. Which does NOT involve an oxidation process?
a) rusting fenders on your car
b) using a flashlight
c) a bonfire
d) melting ice

2. True or false: the following are all examples of redox reactions.
Combustion
Decay
Rust

3. Reducing agents are
a) gives electrons away
b) gains electrons

4. Does an oxidizing agent gain or lose electrons?