What is Salt?
{{otheruses}}[[File:Selpologne.jpg|thumb|Salt crystal]] In [[chemistry]], a '''salt''' is any [[Neutral particle|neutral]] [[chemical compound]] made of [[cation]]s (positive [[ion]]s) attached to [[anion]]s (negative ions). The main kind of salt is [[sodium chloride]] with the chemical formula NaCl. It is formed when [[hydrochloric acid]] is added to [[sodium hydroxide]]. The reaction is as follows HCl+NaOH2 gives NaCl+H20+heat Mixtures of salts in [[water]] are called [[electrolyte]]s. [[Electricity]] is able to pass through electrolytes, as well as molten salts. Salts can melt [[ice]], because salts lower the [[temperature]] needed for [[liquid]] to [[Freezing|freeze]].<ref>{{cite web|url=http://www.sciencebase.com/science-blog/salt-lowers-freezing-point-of-water.html|title=Salt Lowers Freezing Point of Water – David Bradley|website=www.sciencebase.com}}</ref> Because of that, streets are sometimes treated with salt in [[winter]], if the [[temperature]] is only a little below [[freezing]].<ref>{{cite web|url=http://www.science-niblets.org/everyday-science/salt-treatment-for-icy-streets.html|title=Salt treatment for icy streets|date=12 March 2016|publisher=|archive-url=https://web.archive.org/web/20160312015611/http://www.science-niblets.org/everyday-science/salt-treatment-for-icy-streets.html |archive-date=2016-03-12 }}</ref> A salt can also be explained as an [[ionic compound]] which dissociates, forming a positive [[ion]] other than [[hydrogen]] ion, and a negative ion other than hydroxyl ion. == History == Because many [[Germ|germs]] cannot live in salt, it has been used to preserve [[food]]. Its use as a [[food]] preservative helped large amounts of [[food]] to be stored, sent a long way, and eaten all through the year. This helped populations to grow, cities to develop, and soldiers in wars to be fed. Salt was probably used in [[Egypt]] as long ago as [[4th millennium BC|4000 BC]]. In ancient times, salt was more valuable than it is now, because it was hard to get in many places, and could be used not