Question

(iii) A polycrystalline iron sheet lying flat and fully immersed in a dilute acidic solution was observed to turn brown after a period of time. State the type of corrosion cell developed and explain the observation. (5 marks)

Answer 1

A polycrystalline uron sheet dying flat and fully imersed in a dilute acidic solution was observed to tum brown after a periodic of time" Corrosion Type :- Galvanic Costorosion. Galvanic Corraslon occurs when two different metals have physical or electrical contact with each other and are emmersed in a electrolyte, which is dilute acidic en our Condition. or when the same metal is exposed to electrolyte with different concentrations. In a galvanic couple, the more active metal (the anode) Corrodes at an accelerated gate and the mare noble metal (the cathode) corrodes at a slower rate, when immersed Sepesately, each 'metal Corrodes at its own rate. what type of metal (s) to use as readily determined by galvanic Series 1 After immered on in a dilute acldic solution, it was turn's to brown color after a period of time, because of this phenomenon it may be Psevent by electro polishing the metal.