what is stoichiometric and non stoichiometric compounds.explain with examples?

what is stoichiometric and non stoichiometric compounds.explain with examples?


1 Answers

AKASH GOYAL AskiitiansExpert-IITD
420 Points
13 years ago

Dear Pooja

Non-stoichiometric compounds are chemical compounds with an elemental composition that cannot be represented by a ratio of well-defined natural numbers, and therefore violate the law of definite proportions. Often, they are solids that contain crystallographic point defects, such as interstitial atoms and vacancies, which result in excess or deficiency of an element, respectively.

Nonstoichiometry is pervasive for transition metal oxides, especially when the metal is not in its highest oxidation state.[2] For example, although wüstite (ferrous oxide) has an ideal (stoichiometric) formula FeO, the actual stoichiometry is closer to Fe0.95O. The non-stoichiometry occurs because of the ease of oxidation of Fe2+ to Fe3+ effectively replacing a small portion of Fe2+ with two thirds their number of Fe3+. Thus for every three "missing" Fe2+ ions, the crystal contains two Fe3+ ions to balance the charge.

The monosulfides of the transition metals are often nonstoichiometric. Best known perhaps is iron(II) sulfide (mineral pyrrhotite) with a composition Fe(1-x)S (x = 0 to 0.2).


All the best.                                                           


AskiitiansExpert-IIT Delhi


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