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When Fe 2 O 3 ·H 2 O is heated, it loses its water of hydration. Further heating at 1670 K converts Fe 2 O 3 to black Fe 3 O 4 (Fe II Fe III 2 O 4), which is known as the mineral magnetite. Fe(O)OH is soluble in acids, giving [Fe(H 2 O) 6] 3+. In concentrated aqueous alkali, Fe 2 O 3 gives [Fe(OH) 6] 3−. [12]
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 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.
Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe 3 O 4.It occurs in nature as the mineral magnetite.It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe 2 O 3) which also occurs naturally as the mineral hematite.
In liquid water at high temperatures, (e.g. that approaching the critical temperature), the solubility of ionic solutes tends to decrease due to the change of properties and structure of liquid water; the lower dielectric constant results in a less polar solvent and in a change of hydration energy affecting the ΔG of the dissolution reaction.
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 . Organic compounds
Hematite (/ ˈ h iː m ə ˌ t aɪ t, ˈ h ɛ m ə-/), also spelled as haematite, is a common iron oxide compound with the formula, Fe 2 O 3 and is widely found in rocks and soils. [6] Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Fe
Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite. [3] [4] One of several iron oxides, it is a black-colored powder that is sometimes confused with rust, the latter of which consists of hydrated iron(III) oxide (ferric oxide).