What is a common scale-forming substance found in water?

Calcium carbonate is a common scale-forming substance found in water due to its prevalence in many natural water sources. When water contains high levels of calcium ions and carbonate ions, it can lead to the formation of calcium carbonate precipitates under certain conditions, such as changes in temperature or pH. This process can result in scale buildup on pipes, fixtures, and heating surfaces, which can hinder water flow and reduce the efficiency of heating systems.

In contrast, magnesium sulfate, potassium chloride, and sodium bicarbonate are generally not associated with scale formation in the same way. Magnesium sulfate, for instance, is more soluble and does not precipitate as readily under typical water conditions. Potassium chloride does not form scale either, as it remains dissolved in water. Sodium bicarbonate can contribute to alkalinity in water but does not typically result in scale formation comparable to that of calcium carbonate. Understanding the role of calcium carbonate is crucial for water treatment and management, especially in systems that may face scaling issues.