Oxidation- Reduction Reactions

Objectives: Define oxidation, reduction, reducing and oxidizing agent

Gather and evaluate data in order to determine if an oxidation-reduction reaction as taken place

Create a graph of collected data

 Identify independent and dependent variables

Construct a hypothesis

Analyze data; prove or disprove hypothesis by using data

Oxidation Involves a loss of Electrons

• Some books define oxidation as reaction in which a substance gains oxygen or loses hydrogen.

• It is also defined as “a reaction that removes one or more electrons”

• You’ve seen rusted iron and burning wood. Each chemical reaction is fueled by oxygen.

Slow Oxidation

• Slow oxidation: matter links up with oxygen very slowly.

• There is no flame

• Heat is given off, but cannot be felt

• What happens to a potato if cut and left unwrapped?• What happens to an apple when it is cut and left expose

to air? What does lemon juice do to cut apples?

• Ex: rusting of iron, the decay of food, the food we eat oxidizes slowly in order to supply us with the energy to live.

Rapid Oxidation

• Rapid oxidation: oxygen links up with other matter very rapidly. The chemical reaction gives off a flame and a lot of heat.

• The flame is rapid oxidation

• Rapid oxidization is the same as “Combustion” : The oxidizing reaction of an organic compound, in which heat is released.

How can oxidation be prevented?

• To prevent oxidation, you must prevent oxygen from coming into contact with the material

• People paint their cars to prevent the metal from rusting

• Food is wrapped in plastic wrap or aluminum foil

• Stays fresher longer.

Reduction

• Reduction: chemical change in which electrons are gained, either by the removal of oxygen, the addition of hydrogen, or the addition of electrons.

• Think about the addition of lemon juice to a cut apple….oxidation is greatly decreased. • Lemon juice is an acid

• How do you know this? You can visually see that the lemon juice creates a barrier between itself and the environment, the browning effects will not occur as quickly.

Redox reactions

• Oxidation-reduction reactions: any chemical change in which one species loses electrons (oxidized) and another is reduced(gains electrons); also called redox reaction

• Redox reactions saves lives!• Airbags are filled with sodium azide (NaN3) and iron (III) oxide. Upon

impact the mixture is automatically ignited. NaN3 decomposes in a redox reaction to form sodium and nitrogen