THEME: Solution. Coligative properties of biological liquids. Chemistry biogenic elements. Complex compound

in biological systems

LECTURELECTURE 11

associate prof. Dmukhalska Ye. B. preparedassociate prof. Dmukhalska Ye. B. prepared

PLAN1. The main concepts of solutions2. Types of solutions3. Heat effect of a dissolution4. Methods for expressing the concentration of a solution5. Vapour pressure and Raoult’s law6. Collogative properties

• A solution is a homogeneous mixture of two or more substances whose composition can be varied within certain limits

The substances which is used for prepare

the solutions are called components

• The components of a binary solution are solute and solvent.

• Solvent (water) is a component which is present in excess, in other words a solvent is a substance in which dissolution takes place. Solvent doesn’t change its physical state during reaction of dissolution.

• Solute (sodium chloride, sugar) is a component which is present in lesser quantity. Or solute is a substance that dissolves.

TYPES OF SOLUTION1. Depending upon the total components 1. Depending upon the total components

present in the solution:present in the solution:a) Binary solution (two components)b) Ternary solution (three components)c) Quaternary solution (four components)…..etc.2. Depending upon the ability2. Depending upon the ability of the of the dissolution

some quantity of the solute in the solvent:some quantity of the solute in the solvent:A saturated solution is one that is in equilibrium

with excess undissolved solute, or would be in equilibrium if excess solute were present.

An unsaturated solution is one in which the concentration of solute is less than its concentration in a saturated solution.

A supersaturated solution is one in which the concentration of solute is greater than its concentration in a saturated solution.

3. Depending upon the physical states of the solute and solvent, the solution can be classified into the following nine type:

• 4. Depending upon the4. Depending upon the physical state• Gas solution. Gaseous solutions have the structure that is typical of all

gases. Air, the gaseous solution with which we come in closest contact, is composed primarily of N2 (78 % by volume), O2 (21 %), and Ar (1 %), with smaller concentrations of CO2, H2O, Ne, He, and dozens of other substances at very low levels.

• Liquid solutions have the internal structure that is typical of pure liquids: closely spaced particles arranged with little order. Unlike a pure liquid, how ever, a liquid solution is composed of different particles. Much of this chapter is devoted to the properties of liquid solutions, and special emphasis is given to aqueous solutions, in which the major component is water.

• Two kinds of solid solutions are common. The first, the substitutional solid solution, exhibits a crystal lattice that has structural regularity but in which there is a random occupancy of the lattice points by different species.

Concentration units of a solution

The concentration of a solution may be defined as the amount of solute present in the solution.

1. Mass percentage or volume percentageThe mass percentage of a component in a given solution is the

mass of the com ponent per 100 g of the solution.

%100)(

solutionm

solutem

solutesolvent

solute

V)(V

V

• Mass concentration, titer (T) is number grams of solute (m) per one milliliter of solution (V). Or it is the ratio of the quantity grams of solute and volume solution:

)(solutionV

solutemT

2. MolarityIt is the number of moles of the solute dissolved per litre of the solution. It’s represented as M or CM

CM = (М) = Moles of solute / Volume of solution in litres or

CM = (М) = Mass of component A/ Molar mass of A *Volume of solution in litres The unit of molarity is mol/L, 1L = 1000 ml

MV

m

V

n CM

VM

m

v

n C

solutionsolute

solute

solution

soluteM

3. MolalityIt is the number of moles of the solute dissolved per 1000 g (or 1 kg) of the solvent. It’s denoted by m or Cm Cm = (m) = Moles of solute/Weight of solvent in kgorCm = (m) = Moles of solute * 1000/Weight of solvent in gramThe unit of Molality is m or mol/kg

mM

m

m

n C

solventsolute

solute

solvent

solutem

4. Normality:It is the number of gram equivalents of the solute dissolved per litre of the

solution. It’s denoted by N or CN (N)= CN = Number of gram equivalents of solute/Volume of solution in litres

or(N) = CN = Number of gram equivalents of solute *1000 / Volume of solution in ml

Number of gram equivalents of solute = Mass of solute / Equivalent mass of solute

)()( solutionVsoluteE

solutemCn

Relationship between Normality and Molarity of SolutionsRelationship between Normality and Molarity of Solutions

Normality = Molarity * Molar mass/Equivalent massNormality = Molarity * Molar mass/Equivalent mass

5. Mole fraction - 5. Mole fraction - is the number of moles of one substance (na) in the solution divided by the total number of moles of all kinds of substances in the solution. It’s denoted by X. It’s denoted by X.

Raoult’s law for solutions containing non-volatile Raoult’s law for solutions containing non-volatile solutessolutes

Vapour pressure of the solution=Vapour pressure of the solvent in the solution

If is the vapour pressure of the solvent over a solution containing non-volatile solute and is its mole fraction then according to Raolt’s law,

or

At a given temperature , the vapour pressure of a solution containing non-volatile solute is directly proportional to the mole fraction of the solvent

Collogative properties

The dilute solutions of non-volatile solutes exhibit certain characteristic properties which don’t depend upon the nature of the solute but depend only on the number of particles of the solute, on the molar concentration of the solute. These are called colligative properties. Thus

1. Relative lowering in vapour pressure2. Elevation in boiling point3. Depression in freezing point4. Osmotic pressureThis mean that if two solutions contain equal number of solute

particles of A and B then the two solutions will have same colligative properties

The relative lowering in vapour pressure of an ideal solution containing the non-volatile solute is equal to the mole fraction of the solute at a given temperature.

where A is a solvent, B is a solute

Elevation in boiling point

The boiling point of a liquid is the temperature at which its vapour pressure becomes equal to the atmospheric pressure. The boiling point of the solution is always higher than that of the pure solvent. The different in the boiling points of the solution and pure solvent is called the elevation in boiling point

It has been found out experimentally that the elevation in the boiling point of a solution is proportional to the molality concentration of the solution

where is called molal elevation constant or ebullioscopicconstant

Depression in freezing pointThe freezing point is the temperature a which the solid and The freezing point is the temperature a which the solid and

the liquid states of the substance have the same vapour the liquid states of the substance have the same vapour pressure. The freezing point of the solution is always pressure. The freezing point of the solution is always lower than that of the pure solvent.lower than that of the pure solvent.

where is the molal depression constant or molal cryoscopic constant

Determination of Determination of Molar massMolar mass

Osmotic pressure

OSMOSIS.OSMOSIS. I It is the movement of water across a semi-t is the movement of water across a semi-permeable membrane from an area of high permeable membrane from an area of high water potential (low (low solute concentration) to an area of low water potential concentration) to an area of low water potential (high solute concentration). It is a physical process in (high solute concentration). It is a physical process in which a solvent moves, without input of energy, across a which a solvent moves, without input of energy, across a semi-permeable membrane (permeable to the semi-permeable membrane (permeable to the solvent, but , but not the solute) separating two solutions of different not the solute) separating two solutions of different concentrationsconcentrations oror

Osmosis is the phenomenon of the flow of solvent through Osmosis is the phenomenon of the flow of solvent through a semi-permeable membrane from pure solvent to the a semi-permeable membrane from pure solvent to the solution.solution.

Osmosis can also take place between the solutions of Osmosis can also take place between the solutions of different concentrations. In such cases, the solvent different concentrations. In such cases, the solvent molecules move from the solution of low solute molecules move from the solution of low solute concentration to that of higher solute concentration.concentration to that of higher solute concentration.

Osmotic pressure depends Osmotic pressure depends upon the molar upon the molar

concentration of solutionconcentration of solutionVan’t Hoff observed that for dilute Van’t Hoff observed that for dilute

solutions, the osmotic pressure is solutions, the osmotic pressure is given as:given as:

Determination of Molar Mass Determination of Molar Mass from Osmotic Pressurefrom Osmotic Pressure

Conditions for getting accurate value of molar massConditions for getting accurate value of molar mass1.1. The solute must be non-volatile.The solute must be non-volatile.2.2. The solution must be dilute, concentration of the The solution must be dilute, concentration of the

solute in the solution should not be more than 5 %solute in the solution should not be more than 5 %3.3. The solute should not undergo either dissociation or The solute should not undergo either dissociation or

association in the solution.association in the solution.

If two solutions have same osmotic pressure are If two solutions have same osmotic pressure are

called called isotonic solutions or isoosmoticisotonic solutions or isoosmotic solutionssolutionsIf a solution has more osmotic pressure than some other If a solution has more osmotic pressure than some other

solutrion , it is called solutrion , it is called hypertonichypertonicOn the other hand, a solution having less osmosis pressure On the other hand, a solution having less osmosis pressure

than the other solution is called than the other solution is called hypotonichypotonicTo noteTo note that a 0,9% solution of sodium chlorine (known as that a 0,9% solution of sodium chlorine (known as

saline water) is isotonic with human blood corpuscles. In saline water) is isotonic with human blood corpuscles. In this solution, the corpuscles neither swell nor shrink. this solution, the corpuscles neither swell nor shrink. Therefore, the medicines are mixed with saline water before Therefore, the medicines are mixed with saline water before being injected into the veins.being injected into the veins.

5% NaCl solution is hypertonic solution and when red blood 5% NaCl solution is hypertonic solution and when red blood cells are placed in this solution, water comes out of the cells cells are placed in this solution, water comes out of the cells and they and they shrinkshrink

On the other hand, when red blood cells are placed in distilled On the other hand, when red blood cells are placed in distilled water (hypotonic solution), water flows into the cells and water (hypotonic solution), water flows into the cells and they they swell or burstswell or burst

• The effect of hypertonic and hypotonic The effect of hypertonic and hypotonic solutions on animal cells.solutions on animal cells.

• (а) Hypertonic solutions cause cells to (а) Hypertonic solutions cause cells to shrink (crenation) - plasmolysis;shrink (crenation) - plasmolysis;

• (b) hypotonic solutions cause cell (b) hypotonic solutions cause cell rupture - hemolysis; rupture - hemolysis;

• (c) isotonic solutions cause no (c) isotonic solutions cause no changes in cell volume.changes in cell volume.

•Coordination compounds are the compounds in which the central atom (usually metallic), (usually metallic), is linked to а number of ions or neutral molecules by coordinate bonds i.е. by donation of lone pairs of electrons by these ions or neutral molecules to the central metal atom.

• nickel tetracarbonyl, [Ni(CO)4]

A A coordination complexcoordination complex

Complex compounds А) StructureCuSO4 + 4 NH3 = [Cu (NH3)4] SO4

[Cu (NH3)4] SO4

Complex compound• Cu2+ - central atom •NH3 – ligand• [Cu (NH3)4]2+ - complex ion• SO4

2- -anion

Aqueous solutions that contain [Ni(H2O)6]2+, [Ni(NH3)6]2+ and [Ni(en)3]2+ (from left to right). The two solutions on the right were prepared by adding ammonia and ethylenediamine, respectively, to aqueous nickel(II)

nitrate.

Werner’s TheoryWerner’s Theory• Alfred Werner suggested in Alfred Werner suggested in

1893 that metal ions exhibit 1893 that metal ions exhibit what he called what he called primaryprimary and and secondarysecondary valences. valences.– Primary valences were the Primary valences were the

oxidation number for the metal oxidation number for the metal (+3 on the cobalt at the right).(+3 on the cobalt at the right).

– Secondary valences were the Secondary valences were the coordination number, the coordination number, the number of atoms directly number of atoms directly bonded to the metal (6 in the bonded to the metal (6 in the complex at the right).complex at the right).

• The species formed by linking of а number of ions or molecules by co-ordinate bonds to the central metal atom (or ion) carries positive or negative charge, it is called a complex ion (coordination sphera). [Fe(СN)6]

4-, [Cu(NH3)4]2+,

[Ag(CN)2]-

Coordination sphere.Coordination sphere.

• The central atom and the ligands The central atom and the ligands which are directly attached to it are which are directly attached to it are enclosed in square brackets and are enclosed in square brackets and are collectively termed as the collectively termed as the coordination sphere.coordination sphere.

Metal-Ligand BondMetal-Ligand Bond

• This bond is formed between a Lewis This bond is formed between a Lewis acid and a Lewis base.acid and a Lewis base.– The ligands (Lewis bases) have nonbonding The ligands (Lewis bases) have nonbonding

electrons.electrons.– The metal (Lewis acid) has empty orbitals.The metal (Lewis acid) has empty orbitals.

• Transition metals act as Lewis acidsTransition metals act as Lewis acids•Form complexes/complex ionsForm complexes/complex ions

FeFe3+3+(aq) + 6CN(aq) + 6CN--(aq) (aq) [Fe(CN) [Fe(CN)66]]3-3-(aq)(aq)

NiNi2+2+(aq) + 6NH(aq) + 6NH33(aq) (aq) [Ni(NH [Ni(NH33))66]]2+2+(aq)(aq)

Complex with a net charge = complex ionComplex with a net charge = complex ion

Complexes have distinct propertiesComplexes have distinct properties

Lewis acid Lewis base

Complex ion

Lewis acid Lewis base

Complex ion

• Coordination compoundCoordination compound– Compound that contains 1 or more Compound that contains 1 or more

complexescomplexes– ExampleExample

•[Co(NH[Co(NH33))66]Cl]Cl33

•[Cu(NH[Cu(NH33))44][PtCl][PtCl44]]

•[Pt(NH[Pt(NH33))22ClCl22]]

• The donor atoms, molecules or anions, which donate а pair of electrons to the metal atom and form co-ordinate bond with it are called ligands.

LigandsLigands• classified according to the number of classified according to the number of

donor atomsdonor atoms– ExamplesExamples

•monodentate = 1monodentate = 1•bidentate = 2bidentate = 2•tetradentate = 4tetradentate = 4•hexadentate = 6hexadentate = 6•polydentate = 2 or more donor atomspolydentate = 2 or more donor atoms

chelating agents

LigandsLigands

• Monodentate ligandsMonodentate ligands– Examples: Examples:

•HH22O, CNO, CN--, NH, NH33, NO, NO22--, SCN, SCN--, ,

OHOH--, X, X-- (halides), CO, O (halides), CO, O2-2-

– Example ComplexesExample Complexes

•[Co(NH[Co(NH33))66]Cl]Cl33

•KK33 [Fe(SCN) [Fe(SCN)66] ]

LigandsLigands• BidentateBidentate

– ExamplesExamples

•oxalate ion = Coxalate ion = C22OO442-2-

•ethylenediamine (en) = ethylenediamine (en) = NHNH22CHCH22CHCH22NHNH22

•ortho-phenanthroline (o-phen)ortho-phenanthroline (o-phen)– Example ComplexesExample Complexes

•[Co(en)[Co(en)33]]3+3+

•[Cr(C[Cr(C22OO44))33]]3-3-

•[Fe(NH[Fe(NH33))44(o-phen)](o-phen)]3+3+

LigandsLigandsoxalate ion ethylenediamine

CC

O

O O

O 2-CH2

H2NCH2

NH2

NCH

CH

CH

CHCHCH

HC

HCN

CC

C

C

ortho-phenanthroline

Donor

Atoms:*

* ** *

**

LigandsLigandsoxalate ion ethylenediamine

O

C

MM N

CH

LigandsLigands

• ChelationChelation is a process in which a is a process in which a polydentate ligand bonds to a metal ion, polydentate ligand bonds to a metal ion, forming a ring. The complex produced by this forming a ring. The complex produced by this process is called a chelate, and the process is called a chelate, and the polydentate ligand is referred to as a polydentate ligand is referred to as a chelating agent.chelating agent.– ethylenediaminetetraacetate (EDTA) = (Oethylenediaminetetraacetate (EDTA) = (O22C-C-

CHCH22))22N-CHN-CH22-CH-CH22-N(CH-N(CH22-CO-CO22))224-4-

– Example ComplexesExample Complexes•[Ca(EDTA)][Ca(EDTA)]-2-2 •[Co(EDTA)][Co(EDTA)]-1-1

CH2N

CH2

CH2

C

C

CH2 N

CH2

CH2 C

C

O

O

O

O

O O

OO

EDTA

LigandsLigands* Donor Atoms

*

* *

*

**

EDTA

LigandsLigands

C

O

N

H

M

Coordination numberCoordination number • The number of ligand donor atoms that surround The number of ligand donor atoms that surround

a central metal ion in a complex is called the a central metal ion in a complex is called the coordination number coordination number of the metalof the metal

• Originally, a complex implied a reversible Originally, a complex implied a reversible association of molecules, atoms, or ions through association of molecules, atoms, or ions through weak chemical bonds.weak chemical bonds.

• [Ag(СN)[Ag(СN)22]]--, [Cu(NН, [Cu(NН33))44]]

2+2+ and and

[Cr(Н[Cr(Н22О)О)66]]3+3+

Common Geometries of Complexes

Linear

Coordination Number Geometry

2

Example: [Ag(NH3)2]+

Common Geometries of ComplexesCoordination Number

Geometry4tetrahedral

square planarExample:

[Ni(CN)4]2-

Examples: [Zn(NH3)4]2+, [FeCl4]-

Common Geometries of ComplexesCoordination Number

Geometry6

octahedral

Examples: [Co(CN)6]3-, [Fe(en)3]3+

Coordination Number Geometry 8Dodecahedron Cube Hexagonal bipyramid

Charge on the complex ion.Charge on the complex ion.

• The charge carried by а complex ion The charge carried by а complex ion is the algebraic sum of the charges is the algebraic sum of the charges carried by central metal ion and the carried by central metal ion and the ligands coordinated to the central ligands coordinated to the central metal ion. metal ion.

• [Ag (CN)[Ag (CN)22]-]-

• [Cu (NH[Cu (NH33))44]]2+2+

[Fe(CN)6]3-

Complex charge = sum of charges on the metal and the ligands

+3

6(-1)

[Co(NH3)6]Cl2

Neutral charge of coordination compound = sum of charges on metal,

ligands, and counterbalancing ions

neutral compound

+2

6(0) 2(-1)

Oxidation number or oxidation stateOxidation number or oxidation state..• It is а number that represents an electric charge

which an atom or ion actually has or appears to have when combined with other atoms,

• oxidation number of copper in [Cu(NH3)4]2+ is +2 but

coordination number is 4.• oxidation number of Fe in [Fe(СN)6]

3- is + 3 but the coordination number is 6.

• (i) [Cu (NНЗ)4]SO4. • (ii) Fe in [Fe (СN)6]

3-

• (iii)К3[Fe(С2О4)3]. • (iv) [Ni(CO)4].

[Co(NH3)6]Cl2

Neutral charge of coordination compound = sum of charges on metal,

ligands, and counterbalancing ions

neutral compound

+2

6(0) 2(-1)

Nomenclature of Nomenclature of Coordination Coordination

Compounds: IUPAC Compounds: IUPAC RulesRules• The cation is named before the anionThe cation is named before the anion

• When naming a complex:When naming a complex:– Ligands are named firstLigands are named first

•alphabetical orderalphabetical order– Metal atom/ion is named lastMetal atom/ion is named last

•oxidation state given in Roman oxidation state given in Roman numerals follows in parenthesesnumerals follows in parentheses

– Use no spaces in complex name Use no spaces in complex name

Naming Coordination CompoundsNaming Coordination Compounds

Names of Some Common Metallate Names of Some Common Metallate AnionsAnions

Names of Some Common LigandsNames of Some Common Ligands

• [Co(NН[Co(NН33))66]Cl]Cl33, hexaamminecobalt (III) , hexaamminecobalt (III)

chloride.chloride.

• KK22[PtCl[PtCl66], potassium ], potassium

hexachloroplatinate (IV).hexachloroplatinate (IV).

• [Co(NO[Co(NO22)(NH)(NH33))33], ],

triamminetrinitrocobalt (III)triamminetrinitrocobalt (III)

• [PtCl[PtCl44(NH(NH33))22], ],

diamminetetrachloroplatinum (IV).diamminetetrachloroplatinum (IV).

Types of complexes.Types of complexes. • (i) А complex in which the complex ion carries (i) А complex in which the complex ion carries

а net positive charge is called cationic а net positive charge is called cationic complex: [Co(NНcomplex: [Co(NН33)])]

3+3+ClCl33 [Ni(NH [Ni(NH33))66]]2+2+ClCl22

--

• (ii) А complex in which the complex ion carries (ii) А complex in which the complex ion carries а net negative charge is called anionic а net negative charge is called anionic complex: Na[Ag(CN)complex: Na[Ag(CN)22]]

--, K, K44[Fe (CN)[Fe (CN)66]]4-4-

• (iii) А complex carrying no net charge is called (iii) А complex carrying no net charge is called а neutral complex or simply а complex:а neutral complex or simply а complex:

• [Ni(CO)[Ni(CO)44], [CoCl], [CoCl33 (NН (NН33))33]]

1. With one central atom• Ammonia complex [Cu(NH3)4]SO4

• Aqua complex[Al(H2O)6]Cl3• acidic complex K2[PtCl4]• complex with difference ligands K[Pt(NH3)Cl3]• cyclic (chelates)

Polycentral compoyndsChain [Cr(NH3)5 – OH – (NH3)Cr]Cl3 chelaes (CO)5Mn – Mn(Co)5

Main types of complex compounds

MeO

O

O

O

C

CMe

NH2

NH2

CH2

CH2

CO

CH2 CH2

N NH2CHOOC COOHCH2

MeH2C CH2

CO

O O

IsomerismIsomerism

• IsomersIsomers– compounds that have the same compounds that have the same

composition but a different composition but a different arrangement of atomsarrangement of atoms

• Major TypesMajor Types– structural isomersstructural isomers– stereoisomersstereoisomers

Geometric Geometric IsomersIsomers

Polarimetr

Thank you for attention