The organic precipitate, properties, tabular illustration ,applications, precipitation reaction, daily life uses,

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2. Name. MARYAM AKHTAR
DEPT: BS CHEMISTRY
ID: 19002067004
COURSE :Analytical
chemistry
TOPIC: Organic
precipitate and precipitate
equilibria Gary.D CHRISTIAN
Gary.D CHRISTIAN

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 PRESENTATION LAYOUT

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Organic Precipitate

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 Precipitation
process of conversion of a chemical substance into a solid from a solution by
converting the substance into an insoluble form or a super-saturated solution.
 PRECIPITATE
When the reaction occurs in a liquid solution, the solid formed is called
the precipitate.
 PRECIPITANT
The chemical agent that causes the solid to form is called the precipitant.
 A precipitate is a solid that forms out of solution.
 EXAMPLE
It is the mixing of two clear solutions: (1) silver nitrate (AgNO3) and (2) sodium
chloride (NaCl)
 The precipitate forms because the solid (AgCl) is insoluble in water.
 PRECIPITATE

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Properties of Precipitates and
Precipitation Reaction
The precipitation reaction undergoes in aqueous
solutions or medium in an ionic state.
The reaction takes place between ions present in
the aqueous solutions, forming the product
The products formed at the end of precipitation
reaction are the precipitates which are insoluble in
aqueous solutions
Precipitation reactions are known as ionic reactions
since the ions actively take part in the reaction and
form the product.
These reactions depend on the temperature,
concentration of the solution, buffer solution.

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Ethylenediamine ligand
chelating to a metal
with two bonds.
 A chelating agent is a substance whose molecules can form several
bonds to a single metal ion by forming ring structure.
 An example of a simple chelating agent is ethylenediamine.
 A single molecule of ethylenediamine can form two bonds to a
transition-metal ion such as nickel(II), Ni2+.
CHELATION

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 There are also a large number of organic
compounds that are very useful precipitating
agents for Metals.
 Some of these are very selective, and others are
very broad in the number of elements they will
precipitate.
 Organic precipitating agents have the advantages
of giving precipitates with very low solubility in water.
 Most of them are chelating agents that form slightly
soluble, uncharged chelates with the metal ions.
 A chelating agent is a type of complexing agent
that has two or more groups capable of complexing
with a metal ion.
 The complex formed is called a chelate.
ORGANIC PRECIPITATES

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 ORGANIC ANALYSIS
Several organic functional groups or heteroatoms can be determined using precipitation
methods.

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 Many compounds containing metal ions produce precipitates with distinctive colors.
The following are typical colors for various metals.
 Many of these compounds can produce colors very different.
 PRECIPITATE COLOR

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The reaction
quotient (Q)
measures the relative
amounts of products
and reactants
present during
a reaction at a
particular point in
time

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Precipitate equilibria :
solubility product

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PRECIPITATE EQUILIBRIA : SOLUBILITY PRODUCT

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SHORT TERMS TO
PONDER
solubility product:
It is the equilibrium constant
representing the maximum amount of
solid that can be dissolved in aqueous
solution.
precipitate:
A solid that exits the liquid phase of a
solution.
solubility:
The amount of a substance that will dissolve
in a given amount of solvent to give a
saturated solution under specified condition.
 Solubility Equilibria

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 The solubility product constant (Ksp) is the equilibrium constant for a solid that dissolves in an
aqueous solution. All of the rules for determining equilibrium constants continue to apply.
 An equilibrium constant is the ratio of the concentration of the products of a reaction divided by the
concentration of the reactants once the reaction has reached equilibrium.
 Consider this reaction:
Because the AgCl is a solid, its concentration before and after the reaction is the same. The
equilibrium equation can therefore be rearranged as:
SOLUBILITY PRODUCT CONSTANT

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SOLUBILITY PRODUCT CONSTANT
FORMULA

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 For substances in which the ions are not in a 1:1 ratio,
the stoichiometric coefficients of the reaction become the
exponents for the ions in the solubility-product
expression:
EXAMPLES

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 TABLE OF Ksp FOR DIFF SALTS

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 DYNAMIC EQUILIBRIUM
 Solubility equilibrium is a type of dynamic equilibrium.
 It exists when a chemical compound in the solid state is in chemical equilibrium with
a solution of that compound.
 The solid may dissolve unchanged, with dissociation or with chemical reaction with
another constituent of the solvent, such as acid or alkali.
 TEMP. DEPENDENT
Each type of equilibrium is characterized by a temperature-dependent equilibrium
constant.
 SIGNIFICANCE
Solubility equilibria are important in pharmaceutical, environmental and many other
scenarios.
 SOLUBILITY EQUILIBRIA

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 Dissolution of a salt in water is a chemical process
that is governed by the same laws of chemical
equilibrium that apply to any other reaction.
 There are number of special aspects of these
equilibria that set them somewhat apart from the
more general ones that are covered in the lesson set
devoted specifically to chemical equilibrium.
 These include such topics as the
 common ion effect
 the influence of pH on solubility
 supersaturation
 NATURE OF SOLUBILITY EQUILIBRIA

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 PRECIPITATION AND SOLUBILITY PRODUCT
Precipitation reactions occur when cations and anions in
aqueous solution combine to form an insoluble ionic solid called
a precipitate.
Whether or not such a reaction occurs can be determined by using
the solubility rules for common ionic solids.
Because not all aqueous reactions form precipitates, one must
consult the solubility rules before determining the state of the
products and writing a net ionic equation.

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 The solubility of many compounds depends
strongly on the pH of the solution.
 For example, the anion in many sparingly
soluble salts is the conjugate base of a weak acid
that may become protonated in solution.
 In addition, the solubility of simple binary
compounds such as oxides and sulfides, both
strong bases, is often dependent on Ph.
 EFFECT OF PH ON SOLUBILITY

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1.At a certain temperature, the solubility of Fe(OH)2 in water is 7.7 x 10-6 mol/L (M).
Its Ksp can be calculated ,based on the equilibrium equation:
 EQUILIBRIUM EQUATION
Fe(OH)2 ⇌ Fe2+ + 2OH−
 SOLUBILITY PRODUCT :
Ksp=[Fe2+][OH−]2
MOLE
One MOLE of dissolved Fe(OH)2 produces one mole of Fe2+ and two moles of OH–, so therefore:
The solubility of Fe(OH)2 is 7.7 x 10-6 M, this is equal to the value of the change (x)
 CALCULATING THE SOLUBILITY PRODUCT

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 CALCULATING THE SOLUBILITY PRODUCT

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 CALCULATING THE SOLUBILITY PRODUCT

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PREDICTION
OF
PRECIPITATE
Solubility products
are useful in
predicting whether a
precipitate will form
under specified
conditions.
SELECTION OF
CONDITION
It is also helpful in
choosing conditions
under which two
chemical substances
in solution can be
separated by
fractional
precipitation.
DETERMINATION
The solubility
product of a number
of substances have
been experimentally
determined and can
be used to predict
solubility at a
specified
temperature.
 USES OF SOLUBILITY PRODUCT

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 Precipitation reaction helps in
determining a particular
element present in the given
solution.
 These reactions also monitor the
formation of a precipitate when
some chemical is added to
solutions.
 These are used for the
extraction of magnesium from
the seawater.
 The human body also encounters
these reactions existing between
antigens and antibodies.
 Applications Of Precipitation Reaction

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 Precipitation reaction can be used in wastewater
treatment.
 Used in production of the colored pigments for
paints and dyes.
 Removal of toxic chemicals from water.
 Separation of reaction products.
 In wastewater, a frequent presence of heavy
metals be found as compounds of sulphide and
hydroxide.
 So, we can add a source of hydroxide that is
soluble (NaOH Or Na2S) that will result in a
precipitation reaction
 Examples Of Precipitation Reaction In Everyday Life

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