Chemistry:Descaling agent

Short description: Substance used to remove limescale from surfaces

Limescale build-up inside a pipe reduces both liquid flow and thermal conduction from the pipe, so will reduce thermal efficiency when used as a heat exchanger.

A descaling agent or chemical descaler is a liquid chemical substance used to remove limescale from metal surfaces in contact with hot water, such as in boilers, water heaters, and kettles. Limescale is either white or brown in colour due to the presence of iron compounds. Glass surfaces may also exhibit scaling stains, as can many ceramic surfaces present in bathrooms and kitchen, and descaling agents can be used safely to remove those stains without affecting the substrate since both ceramics and glass are unreactive to most acids.

Action

Descaling agents are typically acidic compounds such as hydrochloric acid that react with the calcium carbonate and magnesium carbonate compounds present in the scale, producing carbon dioxide gas and a soluble salt.

CaCO
3 (s) + 2 H+
(aq) → Ca2+
(aq) + CO
2 (g) + H
2O (l)

MgCO
3 (s) + 2 H+
(aq) → Mg2+
(aq) + CO
2 (g) + H
2O (l)

See also

• Central heating system
• Dealkalization of water
• Hard water
• Hydronics
• Limescale
• Pickling (metal)
• Water softening