Chemistry in your cupboard

Limescale is a hard, white, chalky deposit found inside kettles and around taps, sinks and toilet bowls. When rainwater seeps through limestone the acidity of the rain allows it to react to form soluble calcium hydrogencarbonate. When the water evaporates (in a kettle for instance) it leaves behind insoluble calcium carbonate which can be removed by reacting it with acid. This forms the basis of the core product marketed under the brand name Harpic®, Harpic limescale remover.

Links to the curriculum

This section contains information relevant to the following areas of your chemistry curriculum:

• Bonding
• Acid rain
• Equilibrium and Le Chatelier’s principle
• Strong and weak acids