Magnesium carbonate can be divided into light and heavy depending on the crystallization conditions, generally light. The light ones are: MgCO3-H2O, the heavy ones are: 5MgCO3-Mg(OH)2-3H2O, 5MgCO3-2Mg(OH)2-7H2O, 4MgCO3-Mg(OH)2 and 3Mg(OH)2-4H2O. trihydrate salt at room temperature.
Light magnesium carbonate is a white loose powder or friable lump. Odorless, relative density 2.2, melting point 350°C. Stable in air, heated to 700 ℃ to produce carbon dioxide, to produce magnesium oxide, almost insoluble in water, but in water to cause a slight alkaline reaction. Insoluble in ethanol, can be dissolved and bubbled by dilute acid.
Preparation
(1)Magnesite (MgCO2) or dolomite (MgCO3-CaCO3) is treated and refined.
(2)It is refined from the precipitate obtained after the reaction of magnesium sulfate and sodium carbonate.
Identification method
Take 0.2g of magnesium carbonate gradually add dilute hydrochloric acid solution (1+3) mL when...
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