How is stoichiometry used?

How is stoichiometry used?

Stoichiometry is the field of chemistry that is concerned with the relative quantities of reactants and products in chemical reactions In addition, stoichiometry can be used to find quantities such as the amount of products that can be produced with a given amount of reactants and percent yield

Why do we do stoichiometry?

Stoichiometry allows us to make predictions about the outcomes of chemical reactions Predict the volume of a gas which will be produced by a reaction if given the starting amounts of reactants Determine the optimal ratio of reactants for a chemical reaction so that all reactants are fully used

What are stoichiometric defects?

The compounds in which the number of positive and negative ions are exactly in the ratios indicated by their chemical formulae are called stoichiometric compounds The defects do not disturb the stoichiometry (the ratio of numbers of positive and negative ions) are called stoichiometric defects

What are two types of stoichiometric defects?

Types of stoichiometric defects:

  • Vacancy Defects
  • Interstitial defects
  • Frenkel Defects
  • Schottky Defects

What are the types of point defects?

There are 3 types of point defects:

  • Stoichiometric defect
  • Frenkel defect
  • Schottky defect

What is difference between Schottky and Frenkel defect?

Schottky defect occurs in those ionic crystals where difference in size between cation and anion is small In Schottky defect, both cation and anion leave the solid crystal In Frenkel defect, only the smaller ion (cation) leaves its original lattice site; whereas, the anion remains in original lattice sites

What is Frenkel defect?

The Frenkel defect (also known as the Frenkel pair/disorder) is a defect in the lattice crystal where an atom or ion occupies a normally vacant site other than its own As a result the atom or ion leaves its own lattice site vacant

Why does AgBr show both defects?

AgBr shows both Frenkel and Schottky defects because the radius ratio for AgBr is intermediate Ions have Schottky defects when their anions and cations are both absent from the crystal lattice In AgBr, the Ag+ ions and corresponding Br̶̶‒ ions are absent from the crystal lattice causing Schottky defects

What is Schottky defect give an example?

Examples This type of defect is typically observed in highly ionic compounds, highly coordinated compounds, and where there is only a small difference in sizes of cations and anions of which the compound lattice is composed Typical salts where Schottky disorder is observed are NaCl, KCl, KBr, CsCl and AgBr

How is Schottky defect calculated?

The number of Schottky defects (n) present in an ionic compound containing N ions at temperature Tis given by n = Ne E/2KT, where E is the energy required to create ‘n’ Schottky defects and K is the Boltzmann constant If the mole fraction of Schottky defect in NaCl crystal at 2900 K is X

What is sprinkled effect?

In Frenkel defect, an ion is displaced from its lattice place to an interstitial place So, there is no loss or gain of ions in lattice structure It involves only the migration of the ions within the crystal, thus preserving both volume and mass

What is the cause of Schottky defect?

Schottky defect is a type of point defect or imperfection in solids which is caused by a vacant position that is generated in a crystal lattice due to the atoms or ions moving out from the interior to the surface of the crystal

Can Schottky defects exist in K2O?

(1) Yes, Schottky defects can exist in K2O; each defect will consist of one O2- vacancy and two K+ vacancies (2) No, in the strict sense, Schottky cannot exist in K2O if we consider this type of defect to consist of a cation-anion pair; for every O2- vacancy created there must exist two K+ vacancies

What are the conditions and consequences of Schottky defect?

Consequences of Schottky and Frenkel Defects Presence of large number of Schottky defect lowers the density of the crystal When Frenkel defect alone is present, there is no decrease in density The closeness of the charge brought about by Frenkel defect tends to increase the dielectric constant of the crystal

What is Frenkel defect give an example?

Frenkel defects are mostly exhibited in ionic solids where the smaller ion (usually the cation) is dislocated Some examples include AgBr, ZnS, AgCl, and AgI

What is a point defect?

Point defects are atomic scale, ‘zerodimension’ defects in a crystal structure They include missing atoms, “vacancies,” impurity atoms on lattice sites, “substitutional impurities,” impurity atoms in non-lattice locations, “interstitial impurities,” and interstitial atoms from the host lattice, “self-interstitials”

What is crystal defect in chemistry?

Crystal defect, imperfection in the regular geometrical arrangement of the atoms in a crystalline solid These imperfections result from deformation of the solid, rapid cooling from high temperature, or high-energy radiation (X-rays or neutrons) striking the solid

What is the defect?

A defect is a physical, functional, or aesthetic attribute of a product or service that exhibits that the product or service failed to meet one of the desired specifications

What are the types of crystal defects?

  • Point defects (vacancies, interstitial defects, substitution defects)
  • Line defect (screw dislocation, edge dislocation)
  • surface defects (material surface, grain boundaries)
  • Substitutional – one atom is replaced by as different type of atom
  • Interstitial – extra atom is inserted into the lattice structure at a

What are defects in chemistry?

A point defect can be an atom missing from a site in the crystal (a vacancy) or an impurity atom that occupies either a normal lattice site (a substitutional impurity) or a hole in the lattice between atoms (an interstitial impurity) A Frenkel defect is an ion that occupies an incorrect site in the lattice

What are Nonstoichiometric point defects?

Non-stoichiometric defects: The defects which disturb the stoichiometry of the compounds are called non-stoichiometry defects These defects are either due to the presence of excess metal ions or deficiency of metal ions

What is a line defect?

Line defects, or dislocations, are lines along which whole rows of atoms in a solid are arranged anomalously The resulting irregularity in spacing is most severe along a line called the line of dislocation Line defects can weaken or strengthen solids

What is the impurity defect?

Impurity defects are foreign atoms that replace some of the atoms making up the solid or that squeeze into the interstices; they are important in the electrical behaviour of semiconductors, which are materials used in computer chips and other electronic devices

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