Silver Chloride - AgCl

What is Silver Chloride?

Silver chloride is described as a white crystalline chemical compound having the formula AgCl. Silver chloride, present in the test tube, turns into purplish quickly, especially in the case of sunny laboratory due to the silver chloride being split up into both chlorine and silver. Silver chloride can be prepared when the sodium chloride compound is added to the silver nitrate solution; there occurs a white precipitate of silver chloride. Silver chloride is also an example of a well-known salt stain, which is used to impart an amber colour to the glass.

Chloro silver is the other name of silver chloride.

Properties of Silver Chloride

Let us look at the properties of silver chloride as follows.

Physical Properties of Silver Chloride – AgCl

Let us look at the physical properties of silver chloride.

Chemical Properties of Silver Chloride – AgCl

Let us look at the chemical properties of silver chloride.

• Silver chloride undergoes a decomposition reaction in the presence of sunlight to produce chlorine and silver. The chemical reaction for the same can be given as follows:

AgCl → Ag + Cl

• Silver chloride reacts with a base same as ammonia, forming a complex compound known as chloride ion and Silver diammo ion. The chemical reaction for the same can be given as follows:

AgCl + 2NH3 → [Ag(NH3)2]+ + Cl–

Silver Chloride Structure

The solid adopts the structure of fcc NaCl, where every Ag+ ion is surrounded by an octahedron of 6 chloride ligands. Similarly, AgBr and AGF crystallize. However, crystallography depends on the crystallization condition, majorly in the free silver ion concentration.

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Preparation

Silver chloride is given as unusual, where in that, unlike most of the chloride salts, it contains very low solubility. It can be synthesized easily by the process of metathesis, which is combining an aqueous solution of silver nitrate (soluble) with a soluble chloride salt, like cobalt(II) chloride or sodium chloride. The formed silver chloride will precipitate immediately.

Uses of Silver Chloride

Let us look at the important uses of silver chloride as listed below.

• In electrochemistry, the silver chloride electrode is described as a common reference electrode.

• Silver chloride's low solubility makes it a useful addition to pottery glazes for the formation of "Inglaze lustre".

• It has been used as an antidote for mercury poisoning, assisting in mercury elimination.

Silver chloride is also used:

• to make a photographic paper because it reacts with photons to produce a latent image via photoreduction

• in the photochromic lenses, again taking advantage of its reversible conversion to Ag metal

• wound healing products and in bandages

• to create amber, brown, and yellow shades in the manufacturing of stained glass

• as an infrared transmissive optical component since it can be hot-pressed into lens shapes and window

As an antimicrobial agent:

• for the long-term preservation of drinking water in water tanks

• in a few personal deodorant products

Why is Silver Chloride Soluble in Ammonia and Silver Iodide is Insoluble in Ammonia?

Due to the dissociation constant, if we notice the rows of the periodic table, chlorine falls above the iodine which means, it makes stronger ions, and we also know that strong ions contain high dissociation. Moreover, higher dissociation is also known as higher reactivity.

Another way to look at it is from the acid-base point of view.

The base of silver is weak, whereas chlorine acid is strong. When the weak base reacts with a strong acid, it forms acidic salt. It means the salt that produces acidic ph, currently (ammonia), becomes a base when dissolved in water. Thus, chlorine from AgCl reacts with NH₃ to produce NH₄-Cl. Even though the AgCl holds a poor dissociation but the ionized Cl reacts with ammonia and disturbs the equilibrium present between Ag+n Cl-. Hence, more AgCl dissociates to maintain the equilibrium until all the Agcl is consumed.

Furthermore, the acid of iodine and the silver base is weak. Therefore, weak acid reacts with the weak base to form neutral salt with poor dissociation. We can also confirm it by the fact that the solubility of AgI is poorer than the AgCl.

Is AgCl Insoluble in Water?

No, though AgCl and NaCl seem to be similar, the Ag ion's effective nuclear charge is much more compared to the Na+ ion. Thus, according to the Fajan law, it polarizes chloride anion and forms the bond between them more covalently (in NaCl, Na holds an overall positive charge, and chloride holds a negative charge. Hence, there is no electron present between Cl and Na, and thus it is not covalent. Whereas in Cl and Ag, as polarization occurs, the electron residing on Cl- gets towards the Ag+ ion. Therefore, some amount of electric charge comes between Cl- and Ag+ ion and this forms a covalent bond.