The Water Course

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Dissolved Solids

TWC 1.06 – Water Science FAQs

Water Science FAQ


  • What is the difference (if any) between a mineral salt, a dissolved mineral, and a mineral ion?

A salt, in chemistry, refers to any ionic compound (IUPAC, 1990). For example, table salt (sodium chloride) is an ionic compound composed of sodium (Na+) and chloride (Cl–) ions. A mineral refers to chemical compounds formed naturally on rocks or the Earth, not produced by life processes. Thus, mineral salts are naturally occurring ionic compounds, and they include table salt as well as many other salts found or used in brewing water, such as magnesium sulfate (Epsom salts).


A dissolved mineral refers to the mineral substance dissolved in water. When a salt is dissolved in water, it dissociates — its positive and negative ions separate completely. Sodium chloride dissolved in water no longer exists as a compound; it instead exists as individual sodium and chloride ions dissolved in water. A mineral ion refers to any one of these ions.


  • Are all mineral salts also compounds?

A compound is any substance formed of two or more chemical elements chemically bonded together. In solid mineral salts, the elements involved are bonded together with ionic bonds, a type of chemical bond, so these are considered compounds. When salts dissolve in water, the ionic bonds break and the ions dissociate, so the chemical elements are no longer considered a compound.


  • Table salts dissociate in water. Is that also true for mineral salts?

Yes, all salts dissociate completely when dissolved in water. Table salt is one example of a mineral salt.


Some salts are more soluble than others, however, so a less-soluble salt (such as calcium carbonate) might only partially dissolve. In this case, some of the ions will dissolve in water and fully dissociate, but some will remain a solid. Small particles of solid calcium carbonate may spread throughout the water and create a suspension,