In chemistry, salt is an ionic compound which can be formed by acid neutralization and base reaction. The salt consists of a number of related cations (positively charged ions) and anions (negative ions) so that the product is electrically neutral (without net charge). These component ions can be inorganic, such as chloride (Cl - ), or organic, like acetate ( CH
3 CO -
2 ); and can be monatomic, such as fluoride (F - ), or poliatomics, such as sulfate ( SO 2 -
4 ).
Video Salt (chemistry)
Jenis garam
Salt can be classified in various ways. The salt that produces hydroxide ions when dissolved in water is called the alkali salt. The salt that produces an acid solution is acid salt . Neutral salt is a non-acidic or alkaline salt. Zwitterions contain anionic and cationic centers in the same molecule, but are not considered salts. Examples of zwitterions include amino acids, many metabolites, peptides, and proteins.
Maps Salt (chemistry)
Properties
Color
Solid salts tend to be transparent as illustrated by sodium chloride. In many cases, clear opacity or transparency is only related to individual monochristal size differences. Because light bounces off the grain boundary (the boundary between the crystals), the larger crystals tend to be transparent, while the polycrystalline aggregates look like white powders.
Salt exists in various colors, which appear either from anions or cations. As an example:
- sodium chromate is yellow based on chromic ions
- orange dichromate is orange based on dichromate ions
- cobalt nitrate is red due to the chromophores of hydrated cobalt (II) ([Co (H 2 O) 6 ] 2 ).
- copper sulfate is blue due to copper (II) chromophore
- potassium permanganate has a violet color of anion permanganate.
- nickel chloride is usually green from [NiCl 2 (H 2 O) 4 ]
- sodium chloride, magnesium sulfate heptahydrate is colorless or white because the constituent cations and anions are not absorbed in the visible part of the spectrum
Some minerals are salt because they will be dissolved by water. Similar inorganic pigments tend not to be salt, because insoluble is required for fastness. Some organic dyes are salt, but they are almost insoluble in water.
Taste
Different salts can cause all five basic flavors, for example, salted (sodium chloride), sweet (diacetate lead, which leads to lead poisoning if ingested), acids (potassium bitartrate), bitter (magnesium sulfate), and umami or savory (monosodium glutamate).
Odor
Strong acid salts and strong bases ("strong salts") are not volatile and often odorless, while salts of either weak acids or weak bases ("weak salts") can smell like conjugate acid (eg acetates such as acetic acid (vinegar and cyanide such as hydrogen cyanide (almond)) or a conjugate base (eg, ammonium salt such as ammonia) of the component ions.The slow partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of weak salt formation.
Solubility
Many ionic compounds show significant solubility in water or other polar solvents. Unlike molecular compounds, salts dissociate in solution into anionic and cationic components. The lattice energy, the cohesive force between these ions in a solid, determines the solubility. The solubility depends on how well each ion interacts with the solvent, so that certain patterns become real. For example, sodium, potassium and ammonium salts are usually soluble in water. Notable exceptions include ammonium hexachloroplatinate and potassium cobaltinitrite. Most nitrates and many sulfates dissolve in water. Exceptions include barium sulfate, calcium sulfate (slightly soluble), and lead (II) sulfate, in which pair 2/2- leads to high lattice energy. For the same reason, most of the alkali metal carbonate is insoluble in water. Some dissolved carbonate salts are: sodium carbonate, potassium carbonate and ammonium carbonate.
Conductivity
Salt is characteristically an electrical insulator. The liquid salt or salt solution conducts electricity. For this reason, aqueous salts and solutions containing dissolved salts (eg, sodium chloride in water) are called electrolytes.
Melting point
The typical salt has a high melting point. For example, sodium chloride melts at 801 ° C. Some salts with low lattice energy are liquid at or near room temperature. These include the molten salt, which is usually a mixture of salts, and ionic liquids, which usually contain organic cations. This liquid exhibits unusual properties as a solvent.
Nomenclature
The name of the salt begins with the name of the cation (eg, sodium or ammonium ) followed by the anion name (eg, chloride or acetate ). Salt is often referred to simply by the name of a cation (eg, a sodium salt or ammonium salt) or by an anion name (eg, chloride salt or acetic salt ).
Common salt-forming cations include:
- Ammonium NH 4
- Calcium Ca 2 and Fe 3
- Magnesium Mg 2
- Potassium K
- Pyridinium C
5 H 5 NH - Quaternary ammonium NR
4 , R into an alkyl group or aril group - Sodium Na
- Copper Cu 2
Common saline-forming anions (parent acids in parentheses where available) include:
- Acetate CH
3 COO -
(acetic acid) - Carbonate CO 2 - 3 (carbonic acid)
- Chloride Cl - (hydrochloric acid)
- Citrate HOC (COO -
) (CH
2 COO - )
4 (phosphoric acid)
Formation
Salt is formed by chemical reactions between:
- Bases and acids, for example, NH 3 HCl -> NH 4 Cl
- Metals and acids, for example, Mg H 2 SO 4 -> MgSO 4 H 2
- Metals and non-metals, for example, Ca Cl 2 -> CaCl 2
- Bases and acid anhydrides, for example, 2 NaOH Cl 2 O -> 2 NaClO H 2 O
- Basic acids and anhydrides, for example, 2 HNO 3 Na 2 O -> 2 NaNO 3 H 2 O
- Salt can also be formed if the solutions of various salts are mixed, the ions recombine, and the new salt does not dissolve and settle (see: the solubility balance), for example:
Strong Salt
Strong salts or strong electrolyte salts are chemical salts composed of strong electrolytes. This ionic compound dissociates completely in water. They are generally odorless and unchangeable.
Strong salts begin with Na__, K__, NH4__, or they end with __NO3, __ClO4, or __CH3COO. Most metals of classes 1 and 2 form strong salts. A strong salt is very useful when making a conductive compound because its constituent ion allows for greater conductivity.
Weak salt
Weak salts or "weak electrolyte salts", as the name implies, are composed of weak electrolytes. They are generally more volatile than strong salt. They may be similar to the smell of acids or bases that come from. For example, sodium acetate, NaCH 3 COO, smells similar to acetic acid CH 3 COOH.
See also
References
- Mark Kurlansky (2002). Salt: A World History . Walker Publishing Company. ISBN: 0-14-200161-9.
Source of the article : Wikipedia
0 Comments