Weight loss experemint for carbon steel 1 Explain why the co

Weight loss experemint for carbon steel

1: Explain why the corrosion rate of the stainless steel in diluted H2SO4 is lower than that of carbon steel.

2:   Explain why carbon steel corrodes at lower rate in concentrated H₂SO₄ than in the diluted one.

3:   Explain Why HCI attacks the stainless steel more than the diluted H₂SO₄ does, by examining its surface after exposure to those solutions.

Solution

1. As the iron disolves in diluted H2SO4. the corrosion rate of stainless steel in dluted H2SO4 is lower than that of carbon steel

2.carbon steel corrodes at lower rate in concentrated H2SO4 because of passivity. passivity is the phenomenonof relativelyhigh corrosion resistance as a result of deminution of the anodic process.

3.Hydrochloric acid is classed as reducing acid and lacks the oxidising properties that stainless steels need to maintain their \'passive\' corrosion resistant surface layer.The acid is formed as a product of the pitting / crevice corrosion mechanisms in stainless steels and so when hydrochloric acid is present in any \'external environment\' corrosion is promoted.

where as,Sulphuric acid is oxidising when concentrated but is reducing at low and \'intermediate\' concentrations.
The response of most stainless steel types is that in general they are resistant at either low or high concentrations, but are attacked at intermediate concentrations.