Sodium chloride

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Not to be confused with sodium chlorite.
Sodium chloride
Na CL.jpg
Rock salt - halite.
Names
IUPAC name
Sodium chloride
Systematic IUPAC name
Sodium chloride
Other names
Common salt
Halide
Regular salt
Rock salt
Saline
Salt
Sea salt
Table salt
Properties
NaCl
Molar mass 58.44 g/mol
Appearance Colorless crystalline solid
Odor Odorless
Density 2.165 g/cm3
Melting point 801 °C (1,474 °F; 1,074 K)
Boiling point 1,413 °C (2,575 °F; 1,686 K)
35.65 g/100 ml (0 °C)
35.72 g/100 ml (10 °C)
36.00 g/100 ml (20 °C)
36.09 g/100 ml (30 °C)
36.37 g/100 ml (40 °C)
36.69 g/100 ml (50 °C)
37.04 g/100 ml (60 °C)
37.46 g/100 ml (70 °C)
37.93 g/100 ml (80 °C)
38.47 g/100 ml (90 °C)
38.99 g/100 ml (100 °C)
Solubility Insoluble in halocarbons, hydrocarbons
Solubility in ammonia 2.15 g/100 ml (-40 °C)
Solubility in ethanol 0.065 g/100 g (25 °C)
Solubility in ethylene glycol 7.15 g/100 g (25 °C)
Solubility in formic acid 5.21 g/100 g (25 °C)
Solubility in glycerol 10 g/100 g (25 °C)
Vapor pressure ~0 mmHg
Acidity (pKa) 7
Thermochemistry
72.11 J·K−1·mol−1
−411.12 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
3,000 mg/kg (rat, oral)
Related compounds
Related compounds
Lithium chloride
Potassium chloride
Rubidium chloride
Caesium chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium chloride, sometimes referred to as table salt, is an inorganic compound and the sodium salt of hydrochloric acid, with formula NaCl. At room temperature it is a colorless or white crystalline solid. While most commonly known as a flavoring in numerous foods, sodium chloride finds substantial use as a chemical reagent.

Properties

Physical

Sodium chloride is a colorless or white crystalline solid with a cubic crystal structure. It has a salty taste, hence its use as table salt. A very fast way to cool a solution, apparatus, etc. is to immerse the object or container in ice and add salt; the dissolution of salt requires the ice to melt, pulling heat from its surroundings to initiate the phase change. Because table salt is inexpensive and readily available, this is a useful mechanism for generating a cooling bath for exothermic reactions or for dealing with emergency runaway situations.

Chemical

Sodium chloride can serve as a convenient source of either chloride or sodium ions in reaction mixtures, and can also be combined with concentrated sulfuric acid to generate hydrogen chloride or with dilute sulfuric acid to form hydrochloric acid in solution. Table salt is a common electrolyte for electrolysis, as it is a cheap pH neutral ionic compound. It can also be electrolyzed to produce, depending on the conditions, sodium hydroxide and chlorine gas, sodium chlorate, sodium perchlorate, or sodium hypochlorite, all enormously useful, but the process is not necessarily economical or efficient.

Availability

Suitably pure sodium chloride can be bought as uniodized (iodine-free) salt in grocery stores, or in bulk as water-softening tablets at hardware stores, by far the cheapest method. Some types of sodium chloride tablets are labeled 99.9% pure. It will often be sold in the grocery as "pickling salt", though pickling salt sometimes contains calcium. Iodized salt contains only a very small amount of iodide ion, and may not interfere in simple reactions. Though there are many different formulas for rock salt (used to de-ice roads), brands that contain only sodium chloride may be a good purchase for those that don't want to buy massive amounts of water purification tablets but also don't want to spend lots of money on food-grade salt.

Preparation

Though it is not economical to do so, sodium chloride is easily synthesized by neutralizing sodium bicarbonate, sodium carbonate, or sodium hydroxide with hydrochloric acid. It is the byproduct of the decomposition of sodium perchlorate, which also produces oxygen.

Sodium chloride will also be produced as side product in several reactions, such as the decomposition of sodium hypochlorite:

3 NaOCl → NaClO3 + 2 NaCl

Projects

Handling

Safety

Excess consumption of table salt has been linked with many illnesses. No safety measures are necessary when dealing with sodium chloride under normal conditions.

Storage

Sodium chloride should be stored in closed bottles, as it is slightly hygroscopic. Do not store it in metallic containers, as they might rust.

Disposal

Sodium chloride can be safely poured down the drain. Avoid dumping it in the ground in places where any useful plants grow, as it will kill plants. Pouring it in the ground into a jungle of stinging nettles, hogweed or other vile weeds is okay.

References

Relevant Sciencemadness threads