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In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". [1] [2] The solid formed is called the precipitate. [3] In case of an inorganic chemical reaction leading to precipitation, the chemical reagent causing the solid to form is called the precipitant. [4]
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.
Some sources claim that Mn(OH) 3 is the brown precipitate, but hydrated MnO 2 may also give the brown colour. 4 Mn(OH) 2 (s) + O 2 (aq) + 2 H 2 O → 4 Mn(OH) 3 (s) The second part of the Winkler test reduces (acidifies) the solution. The precipitate will dissolve back into solution as the H + reacts with the O 2− and OH − to form water.
Lead(II) thiocyanate can be formed from the acidification of lead(II) nitrate, Pb(NO 3) 2, with nitric acid, HNO 3, in the presence of thiocyanic acid, HSCN.It may also be made by reacting lead(II) acetate (Pb(CH 3 COO) 2) solved in water with either potassium thiocyanate (KSCN) or ammonium thiocyanate (NH 4 SCN), thus causing a white precipitation of solid lead(II) thiocyanate according to ...
This is a list of unsolved problems in chemistry. Problems in chemistry are considered unsolved when an expert in the field considers it unsolved or when several experts in the field disagree about a solution to a problem.
In chemistry, coprecipitation (CPT) or co-precipitation is the carrying down by a precipitate of substances normally soluble under the conditions employed. [1] Analogously, in medicine, coprecipitation (referred to as immunoprecipitation) is specifically "an assay designed to purify a single antigen from a complex mixture using a specific antibody attached to a beaded support".
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.
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.