Removal of Artefacts (2 Viewers)

[wrxsti]

i know when you remove an artefact from the ocean it undergoes crystillisation so it gets destroyed...

my teacher also goes that removing an artefact will cause HCL to form as the hydrated metal chloride reacts with oxygen gas producing HCL which can damage the artefact...

i havent seen this on any website or book ... is that actually true ? :S:S:S:S

her equation: 4FeCl.H20 +O2 -> 2Fe2O3 + 8HCL

 

[mike 1989]

Not sure about the equation but it does happen, the Fe(OH)Cl decomposes into HCl and other products, which can greatly accalerate corrosion. This however only happens as the article dries out so artefacts are generlly kept wet untail restoration can occur. The Fe(OH)Cl is removed by soaking in NaOH, the OH ions displacethe Cl forming Fe(OH)2 and Cl-, the Cl ions are then washed out.

THis can be found in Conquering Chmistry by Roland Smith and the Excel Chemisrt Study Guide

 

[Forbidden.]

The salt crystallises out of the solution increasing in size and is capable of rupturing the structure of tjhe artefact.