Sodium chloride

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 colourless 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 electrolyses, as it is a cheap pH neutral ionic compound. It can also be electrolysed 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. 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 ammounts 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.

Safety

No safety measures are necessary when dealing with sodium chloride under normal conditions.