gyg Flashcards
(13 cards)
What is rust?
A hydrated form of ferric oxide, Fe2O3.xH2O
Rust is a brown coating that forms on iron when it is left in a moist atmosphere.
What are the main components required for rusting?
Moisture, oxygen, and carbon dioxide
These components are present in the atmosphere and are essential for the rusting process.
Which theory of rusting is considered the most convincing?
Electrochemical theory of rusting
This theory describes rusting as an electrochemical process involving oxidation and reduction reactions.
What occurs at the anode during rusting?
Oxidation of iron and dissolution of metal
The anode is where the portion of iron at lower electrical potential loses electrons.
Write the half-reaction occurring at the anode.
Fe → Fe²⁺ + 2e⁻
This reaction indicates the oxidation of iron, where it loses electrons.
What happens to the electrons liberated at the anode?
They migrate to the cathode
Electrons flow through the metal to the portion at higher electrical potential.
What is the dominant reaction at the cathode during rusting?
Reduction of oxygen
In natural water, the reduction of oxygen is the primary reaction occurring at the cathode.
Write the half-reaction for the reduction of oxygen at the cathode.
O2 + 2H2O + 4e⁻ → 4OH⁻
This reaction shows how oxygen is reduced at the cathode during rusting.
What is formed as a result of the anodic and cathodic reactions?
Ferrous hydroxide, Fe(OH)2
This product is formed from the migration of anodic and cathodic products.
What happens to ferrous hydroxide in the presence of oxygen and water?
It is oxidized to ferric oxide
The oxidation process leads to the formation of ferric hydroxide, which is unstable.
What is the final product of the rusting process?
Ferric oxide, Fe2O3
Ferric oxide can absorb moisture and forms rust.
Fill in the blank: Rust is formed when _______ absorbs moisture from the atmosphere.
Fe2O3
Ferric oxide forms a non-coherent brown hydrated ferric oxide known as rust.
What is the chemical equation for the transformation from ferric hydroxide to ferric oxide?
2 Fe(OH)3 → Fe2O3 + 3H2O
This reaction shows the loss of water from ferric hydroxide to produce ferric oxide.
