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A number of other descriptive terms are also used to qualify the extent of solubility for a given application. For example, U.S. Pharmacopoeia gives the following terms, according to the mass m sv of solvent required to dissolve one unit of mass m su of solute: [8] (The solubilities of the examples are approximate, for water at 20–25 °C.)
The tables below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at one atmosphere pressure. Units of solubility are given in grams of substance per 100 millilitres of water (g/100 ml), unless shown otherwise. The substances are listed in alphabetical order.
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
The compounds are almost insoluble in water, weak acids, and (NH 4) 2 S/(NH 4) 2 S 2 solution is the key for separation of lead from analytical groups I to III elements, tin, arsenic, and antimony. The compounds dissolve in nitric and hydrochloric acids, to give elemental sulfur and hydrogen sulfide, respectively. [ 7 ]
The following compounds are liquid at room temperature and are completely miscible with water; they are often used as solvents. Many of them are hygroscopic.
For example, among the alcohols, ethanol has two carbon atoms and is miscible with water, whereas 1-butanol with four carbons is not. [3] 1-Octanol, with eight carbons, is practically insoluble in water, and its immiscibility leads it to be used as a standard for partition equilibria. [4]
Many phosphates are soluble in water at standard temperature and pressure. The sodium, potassium, rubidium, caesium, and ammonium phosphates are all water-soluble. Most other phosphates are only slightly soluble or are insoluble in water. As a rule, the hydrogen and dihydrogen phosphates are slightly more soluble than the corresponding phosphates.
Cosolvents improve solubility between non-miscible phases, as demonstrated by a solute dissolved in organic solvent but insoluble in water (left). A cosolvent miscible in both phases and able to dissolve the solute is added to form a homogeneous solution of water, organic solvent, and compound (right).