Sotaicho

Hey Comon, Yes, I do agree with that and that was actually the first thing I thought of but a few others disagreed with that and argued that it only proves that dichromate doesn't reduce but the dichromate as a solution could have oxygen dissolved and cause the iron to corrode just as in other solutions like sodium chloride. I did also argue that iron won't corrode in basic solutions with excess OH- ions, a situation which the dichromate produces to a very small extent but the concentration of excess protons and hydroxide ions in water would be rather low initially so it seemed unlikely to be enough.

You say "stainless steel" but Na2Cr2O7 inhibits corrosion of steel as well... unless normal steel also has a small percentage of chromium?

This was one idea I did have but when I read this page: http://en.wikipedia.org/wiki/Chromate_conversion_coating It mentions that "It cannot be applied directly to steel or iron... Phosphate coatings on iron and steel may also be treated with a chromic acid rinse to enhance the phosphate coating" so it appears that it might not be some chromate coating. Also, looking at standard reduction tables, wouldn't the solution need to be acidic to form Cr metal? Unless there is another reduction path for chromate(VI) ions to reduce without an acidic solution?

Hi everyone, I was wondering why Na2Cr2O7 inhibits the corrosion of metallic iron and I was discussing this with some friends today but we were only able to make some educated guesses so I've been on the internet for a few hours now searching for an answer but I've had no success so far. I then remembered a comment my Chemistry teacher told me once about this great science forum, so now I find myself here for the first time with my first post. If anyone knows or has any idea why Na2Cr2O7 inhibits the corrosion of metallic iron then I'll be interested. Thanks