Corrosion of Aluminium by Trona

This book clearly shows the reason why aluminium pots have pitting corrosion. Since aluminium corrodes in alkaline solution addition of Trona to water produces alkaline solution which corrodes aluminium. Though aluminium is passive in nature that is it forms a protective oxide firm that prevent further corrosion this passive firm is however broken when table salt is added to the food cooked in aluminium pot due to the presence of chloride ion that attacks the passive firm when table salt is added to the food cooked in aluminium pot. Consequently aluminium is consumed in food cooked when trona and or table salt is added.