Rusting - DM

Question 1

What is needed for rusting

Answer 1

water and oxygen and iron

Question 2

What colour is rust and what does this suggest

Answer 2

orange/brown so Fe³⁺ is present

Question 3

How does rusting occur

Answer 3

see photos (must know all)

Question 4

3 main things to prevent rusting

Answer 4

sacrificial protection, galvanising, barrier protection

Question 5

Sacrificial protection for rusting definition

Answer 5

using a more reactive metal (often in lumps) with a more negative E^θ value. The more reactive metal is preferably oxidised

Question 6

Galvanising for rusting definition

Answer 6

thin layer of zinc over the metal which forms zinc oxide. If scratched the zinc reacts in preference to iron

Question 7

Barrier protection for rusting definition

Answer 7

stops oxygen and water reaching the surface of the metal - plastic paint

Question 8

Why is rusting worse near the sea

Answer 8

as NaCl (aq) increases conductivity of water so better flow of ions (sort of salt bridge)