[Ethanescence]

Someone said that:

Fe + 2HCl -----> FeCl2 + H2

If there still remains Fe in the solution, doesn't that mean if the final mass of the Fe is weighed, plus the FeCl2 filtrate, then shouldn't there be a gain in mass because of the extra Cl2 being weighed (when compared to inital mass of iron)? Not a loss?

Note: Used around 0.1 to 0.3 mol solution of HCl in seawater (200ml) with 1.65 g mild-steel nail (initial mass) for 5 days.

How can I work out the mass of corrosion (rust) formed (Fe2O3) when there's FeCl2 forming also? What other weights do I need, or how can I work it out from the weights I already have?

The nail had a final mass of 0.88. The filtrate mass was inaccurate, but ranged from around 0.22 g to 1 g.

You do not need to use these masses, it is fine to use general masses/equations so I can just get the general idea.

Thanks so much.

[Borek]

Iron nail lost mass, that's what the statement refers to.

You are right that the iron didn't disappeared, just now it is present in the precipitate.