# Mechanism of action for Citric Acid as a cleaning agent for limescale?

This may be a silly question, but I am not that certain I understand this process because of the low solubility of Calcium Citrate.

How does citric acid actually clean limescale? How much limescale can be cleaned (dissolved in water) in a container with 1 liter of water and limescale under room temperature?

Thanks!

• Limescale is essentially calcium carbonate. This question might be helpful. – Martin - マーチン Sep 8 '16 at 11:03
• Citric acid has a low first pKa (3.13) to protonate limescale (mainly $CaCO_3$) and it can chelate anions like $Ca^{2+}$. Both will help removing limescale. You describe calcium citrate as poorly soluble in water, but the figures show it is much more soluble than calcium carbonate: 0.95 g/L vs 0.013 g/L at 25°C (so 73 times more soluble). – SteffX Sep 8 '16 at 17:34
• @Martin-マーチン The question you describe deals with HCl which will produce Calcium Chloride which is highly soluble in water. My question is different because Calcium Citrate is not very soluble in water. – Reed Sep 12 '16 at 14:10
• I would say it's soluble enough to the extend that colloidal particles will be washed away. – Martin - マーチン Sep 13 '16 at 1:30