Corrosion Flashcards
(21 cards)
Define corrosion
the reaction of metals to form compounds causing their properties to change
metal + oxygen →
metal oxide
metal + water →
metal hydroxide + hydrogen
metal + acid →
salt + hydrogen
CO₂ + H₂O →
H₂CO₃
SO₂ + H₂O →
H₂SO₃
What is Al³⁺ used for?
airplanes
Write an ionic equation for:
Al + H₂SO₃ → Al₂(SO₃)₃ + H₂
What happens when the electrons move from Al to H⁺ ions?
2Al(s) + 3H₂SO₃(aq) → Al₂(SO₃)₃(aq) + 3H₂ (g)
2Al + 6H → 2Al ³⁺ + 3H₂
The properties of the metal changes
Where does corrosion happen?
at the surface of metals
Since metal oxides are insoluble, what happens when they corrode?
a protective layer is formed
Why does aluminium appear much less reactive than is actually is?
because when the aluminium reacts with the oxygen from the air, it creates a protective layer and therefore the pure metal cannot corrode.
What happens when iron reacts with oxygen/water?
it corrodes and rusts
Complete the equation:
iron + oxygen + water →
hydrated iron(lll)oxide
What does hydrated iron(lll)oxide represent?
rusting
What look does rust have?
a flaky look
Does rust protect the iron underneath it?
no, oxygen and water can still enter through the flakes of rust and the iron underneath it can still react
What are the 2 methods that could be used to protect iron?
1) cover iron with paint, oil, or other metal (best option)
2) sacrificial protection
Explain sacrificial protection used on iron
cover iron with a more reactive element that reacts instead of the iron
What is the only metal that when used for sacrificial protection has another name? What is that name?
Zn - galvanising
What is an experiment that can be used to show the conditions of iron for rusting?
tt 1 - iron, water, air
tt 2 - iron, boiled water, oil
tt 3 - iron, air, CaCl₂
tt 4 - iron, water, salt, air
tt - test tube
What are the results for the experiment to show conditions of Fe for rusting and why?
tt 1 - rust
tt 2 - no rust because boiled water removes oxygen and oil prevents oxygen from entering
tt 3 - no rust because CaCl₂ is anhydrous so it removes water
tt 4 - rusts lots because salt is the catalyst for rusting
tt - test tube
