Unit 3- Corrosion Flashcards
Is the rate of corrosion the same with every metal
No different metals corrode at different rates
What is corrosion?
A chemical reaction which involves the surface if metal changing from an element to a compound
What does rusting mean?
It is the term used for the corrosion of iron only
What is required for rusting?
Water and oxygen
What happens to the iron when it rusts?
Initially the iron atoms lose 2 electrons to form iron(ll) ions which can be oxidised further to give iron(lll) ions
What happens to the electrons lost during rusting?
They are accepted by the water and the oxygen to form hydroxide ions
What does feroxyl indicator used for?
It turns blue in the presence of Fe2+ ions
It turns pink in the presence of hydroxide ions
What natural occurrence increases the rate of corrosion?
Acid rain
What does salt in the roads do to cars?
It increases he rate of corrosion on car body work
What happens when iron is attached to metals higher in the electrochemical series?
The electrons flow into the iron preventing rusting from taking place
What happens when iron is attached to metals lower in the electrochemical series?
The electrons flow from the iron accelerating the rate of rusting
When does iron not rust?
When attached to the negative terminal a battery
Name 3 things which have anti-corrosion methods applied to them
- buildings
- cars
- food cans
Name 6 ways which provide physical protection against corrosion
Painting Greasing Electroplating Galvanising Tin-plating Coating with plastic
What does galvanising provide for iron?
The electrons flow to the iron giving the iron sacrificial protection
