The Thermite Process

A very violent reaction that liberates vast quantities of heat results in the formation of molten iron

Purpose

To observe the extremely violent reaction that leads to the formation of iron from its oxide (ore)

A regulus is the metallic mass that forms beneath the slag at the bottom of a crucible

Demonstration

Reaction is very energetic and exothermically so

Possibility of explosion if water is present in the thermite mixture

Temperatures exceed 4500°F

Concepts

Single replacement reactions

Exothermic reactions

Redox reactions

Single Replacement Reactions General type of inorganic reaction

2Al(s)+Fe2O3(s) Al2O3(s)+2Fe(l)

Oxide anions are transferred during reaction from iron(III)oxide to aluminum

Oxidation number of Fe is 3+ in starting material and zero in product

Oxidation number of Al is 0 in starting material and 3+ in product

Oxidation number of oxygen is taken as 2-

Exothermic Reactions

Heat flows out of system

Surroundings heat up

Amount of energy liberated equals -730 kJ/mol

where kJ stands for “kilojoules” a unit of energy, and “mol” stands for the quantity of matter known as a “mole”

Redox Reactions “Transfer of electrons” reaction

Redox means “reduction-oxidation”

Al(s) gave its electrons to Fe2O3(s)

Al(s) was oxidized

Fe2O3(s) was reduced

Conclusions Single replacement reaction defined by

the transfer of oxide anion from Fe2O3 to Al2O3 in this demonstration

Reaction demonstrates concept of heat flow

Al(s) gave up electrons so is the reducing agent

Fe2O3(s) gained electrons so it the oxidizing agent

Comments

Applications in welding and military incendiary weapons

Discovered by Hans Goldschmidt in 1895

Extremely dangerous reaction that should not be performed by students

Quiz

1. Who invented the Thermite Process?

2. What is being oxidized in this reaction?

3. What are two applications of this process?

4. What is being reduced in this reaction?

5. Give a definition of an exothermic process.

Answers1. Hans Goldschmidt

2. Aluminum metal is being oxidized to aluminum oxide

3. Welding and military incendiary weapons are a few applications

4. Iron oxide is being reduced to iron metal

5. Heat flows out of a system and the surrounding heat up