Salt
Definition and meaning of Salt in chemistry.
Salt is an ionic compound made of a positively charged cation and a negatively charged anion held together by strong ionic bonds. The cation typically comes from a base, and the anion typically comes from an acid. Salts form solid crystals at room temperature and dissolve readily in water.
In more detail
Salts most commonly form through a neutralization reaction, in which an acid reacts with a base to produce a salt and water. The reaction releases heat because forming the strong ionic bonds in a product like NaCl, along with a stable water molecule, is energetically favorable.
In their dry, solid state, salts arrange into a rigid, repeating pattern called a crystal lattice, which makes them hard and brittle with high melting points. When a salt dissolves in a polar solvent like water, or when it melts, its lattice breaks apart into freely moving ions.
These free ions let the solution or melt conduct electricity, which is why salts are classified as electrolytes. Sodium chloride, ordinary table salt, is the most familiar example, but the term salt covers an enormous range of compounds, from baking soda to the calcium salts found in bone.
A salt's acidity or basicity in solution depends on the strength of the acid and base that formed it. Some salts, called hydrates, even trap water molecules within their crystal structure, such as copper(II) sulfate pentahydrate, which is blue, compared to the white anhydrous form.
Key facts
| Field | General Chemistry |
|---|---|
| Composition | A cation and an anion |
| Formation | Acid-base neutralization |
| Example formula | NaCl (sodium chloride) |
| Solid-state structure | Rigid, repeating crystal lattice |
| Behavior in solution | Dissociates into ions and conducts electricity (electrolyte) |
When hydrochloric acid, HCl, reacts with sodium hydroxide, NaOH, the products are water and the salt sodium chloride, NaCl. This is a classic acid-base neutralization reaction. Both starting materials are dangerous to handle in concentrated form, but the salt product is safe enough to eat. A similar reaction between sulfuric acid and calcium hydroxide produces the salt calcium sulfate along with water.
Frequently asked questions
Are all salts safe to eat?
No. Many salts are highly toxic, such as lead(II) nitrate. Only specific salts like sodium chloride are safe for consumption in appropriate amounts.
What makes a salt acidic or basic?
A salt can be acidic, basic, or neutral in solution depending on the relative strength of the acid and base that reacted to form it.
Why do salts conduct electricity when dissolved?
Dissolving breaks the crystal lattice apart into freely moving, charged ions. These mobile ions carry electric current through the solution.
Related terms
Sources & references
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