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This can be due to temperature changes, solvent evaporation, or by mixing solvents. Precipitation occurs more rapidly from a strongly supersaturated solution. The formation of a precipitate can be caused by a chemical reaction. When a barium chloride solution reacts with sulphuric acid, a white precipitate of barium sulphate is formed.
The reaction product is a greyish to white precipitate. This is the same synthesis from Berthelot in which he first found silver acetylide in 1866. [4] The double salt is formed in acidic or neutral silver nitrate solutions. Performing the synthesis in basic ammonia solution does not allow the double salt to form, producing pure silver ...
The formation of a reddish-brown precipitate indicates Fe 3+; a gelatinous white precipitate indicates Al 3+; and a green precipitate indicates Cr 3+ or Fe 2+. These last two are distinguished by adding sodium hydroxide in excess to the green precipitate. If the precipitate dissolves, Cr 3+ is indicated; otherwise, Fe 2+ is present.
For example, reaction with sodium sulfide produces the brown/black tin(II) sulfide: SnCl 2 (aq) + Na 2 S (aq) → SnS (s) + 2 NaCl (aq) If alkali is added to a solution of SnCl 2, a white precipitate of hydrated tin(II) oxide forms initially; this then dissolves in excess base to form a stannite salt such as sodium stannite:
Soap scum or lime soap is the white solid composed of calcium stearate, magnesium stearate, and similar alkaline earth metal derivatives of fatty acids. These materials result from the addition of soap and other anionic surfactants to hard water.
If the substance lacks the ability to dissolve in water, the molecules form a precipitate. [3] When writing the equations of precipitation reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility. Soluble compounds are aqueous, while insoluble compounds are the precipitate.
Precipitated silica is an amorphous form of silica (silicon dioxide, SiO 2); it is a white, powdery material. Precipitated silica is produced by precipitation from a solution containing silicate salts. The three main classes of amorphous silica are pyrogenic silica, precipitated silica and silica gel.
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.