Inorganic salts, melting points

Infrared (IR) spectroscopy, and intermediates, 20 and electrolytic solutions, 340 Inorganic salts, melting points, 604 Interactions... 

Table 21.2.1. Melting points of various inorganic salts, melting points given in °C...

Hydrated inorganic salts Melting point rc) Melting heat (kJ/kg) Density (kg/m ) Specific heat capacity (J/(kgK)) Heat storage density (MJ/m )... 

The table below gives the lowest temperature that can be obtained from a mixture of the inorganic salt with finely shaved dry ice. With the organic substances, dry ice (—78°C) in small lumps can be added to the solvent until a slight excess of dry ice remains or liquid nitrogen (—196°C) can be poured into the solvent until a slush is formed that consists of the solid-liquid mixture at its melting point. 

What constitutes an ionic liquid, as distinct from a molten salt It is generally accepted that ionic liquids have relatively low melting points, ideally below ambient temperature [1, 2]. The distinction is arbitrarily based on the salt exhibiting liquidity at or below a given temperature, often conveniently taken to be 100 °C. However, it is clear from observation that the principle distinction between the materials of interest today as ionic liquids (and more as specifically room-temperature ionic liquids) and conventional molten salts is that ionic liquids contain organic cations rather than inorganic ones. This allows a convenient differentiation without concern that some molten salts may have lower melting points than some ionic liquids . 

An ionic liquid (IL) is a substance that is composed entirely of ions, and is a liquid at room temperature. Frequently the ionic liquid consists of organic cations and inorganic anions, although it is not limited to these combinations. While some people have said that the ionic liquid can have a high melting temperature such as in the case of the molten salt form of NaCl, the most commonly held understanding of this term is one that has a melting point of less than 100 °C, more preferably less than 50 °C. For example, many preferred ionic liquids are liquid at room temperature, or less. 

In MSO processing, organic wastes are chemically broken down to carbon dioxide, nitrogen gas, and water vapor in a bath of molten salt. The salt may be of various compositions, with variable melting points. Inorganic materials react with the salt mixture, producing ash and salts for subsequent treatment or disposal. The oxidation takes place at lower temperatures than incineration or other combustion technologies. 

The general observations made regarding structural influences on melting points are transferable across cation type, and apply in each case. The primary focus is on l-alkyl-3-methylimidazolium cations, coupled with simple organic and inorganic anions. Complex anions, such as mixed /MX systems, are mentioned, as are other series of cations (including some examples of tetraalkylammonium salts). 

Table 3.12. Melting points (f p), boiling points (ftp), and liquid range At = ftp — of some fused inorganic and organic salt systems in °C (Janz, 1967 Gordon, 1969).

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