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

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 Fe_0.95O. 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.                                                           

AKASH GOYAL

iitd.akash@gmail.com

AskiitiansExpert-IIT Delhi

Please feel free to post as many doubts on our discussion forum as you can. We are all IITians and here to help you in your IIT JEE preparation.

Win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.

Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar  respectively : Click here to download the toolbar..