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A typical reaction with silver nitrate is to suspend a rod of copper in a solution of silver nitrate and leave it for a few hours. The silver nitrate reacts with copper to form hairlike crystals of silver metal and a blue solution of copper nitrate: 2 AgNO 3 + Cu → Cu(NO 3) 2 + 2 Ag. Silver nitrate decomposes when heated:
The equipment required is a colorimeter, some cuvettes and a suitable color reagent. The process may be automated, e.g. by the use of an AutoAnalyzer or by flow injection analysis . Recently, colorimetric analyses developed for colorimeters have been adapted for use with plate readers to speed up analysis and reduce the waste stream.
The solution needs to be near neutral, because silver hydroxide forms at high pH, while the chromate forms Ag 2 Cr 2 O 7 or AgHCrO4 at low pH, reducing the concentration of chromate ions, and delaying the formation of the precipitate. Carbonates and phosphates precipitate with silver, and need to be absent to prevent inaccurate results.
The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, precipitation and other visible changes. [ 1 ] [ 2 ] Qualitative inorganic analysis is that branch or method of analytical chemistry which seeks to establish the elemental composition of inorganic compounds ...
The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy .
Silver nitrite is much less soluble in water than silver nitrate, and a solution of silver nitrate will readily precipitate silver nitrite upon addition of sodium nitrite: AgNO 3 (aq) + NaNO 2 (s) → NaNO 3 (aq) + AgNO 2 (precipitate) Alternatively, it can be produced by the reaction between silver sulfate and barium nitrite.
In one of the most famous reactions in chemistry, the addition of colorless aqueous silver nitrate to an equally colorless solution of sodium chloride produces an opaque white precipitate of AgCl: [14] Ag + (aq) + Cl − (aq) → AgCl(s) This conversion is a common test for the presence of chloride in solution.
Silver carbonate can be prepared by combining aqueous solutions of sodium carbonate with a deficiency of silver nitrate. [8] 2 AgNO 3 (aq) + Na 2 CO 3 (aq) → Ag 2 CO 3 (s) + 2 NaNO 3 (aq) Freshly prepared silver carbonate is colourless, but the solid quickly turns yellow. [9]