SALT ANALYSIS

 

Objective  :: Concept of ions and formula designing by criss –cross method

 

IONS  ::  Ions are the atoms or a group of atoms formed either by lose of gain of  electron(s).

 

TYPES OF IONS  ::

Cations( + vely charged ions )[More proton than electrons]

Anions (-vely charged ions ) [less  proton than electrons]

 

Polyatomic ions and Monoatomic ions

Monoatomic ions are formed from single atom ( Na+,  Cl-) while polyatomic ions are formed from group of atoms (NH4 +  , SO42-  )

ATOMICITY  . The no. of atoms present in one molecule of the substance is called its atomicity. Eg Atomicity of sulphur is 8 phosphorous is 4.

Valency : The combining capacity of an element is said to be its valency

 

Element/ionic species

Symbol/Formula

Atomicity

Charge

Ferous/Iron(II)

Fe2+

----------

2

Feric /Iron (III)

Fe 3+

----------

3

Mercurous/Mercury(I)

Hg+

----------

1

Mercuric (II)

Hg2+

----------

2

Silver

Ag+

----------

1

Ammonium

NH4 +

----------

1

Stanous/Tin(II)

Sn2+

----------

2

Stanic/Tin(IV)

Sn4+

----------

4

Aluminium

Al3+

----------

3

Lead(II)

Pb2+

----------

2

Copper /Copper (II)

Cu2+

 

2

Potassium

K+

----------

1

Chloride

Cl-

----------

-1

Hydroxide

OH-

----------

-1

Cyanide

CN-

----------

-1

Bicarbonate/hydrogen carbonate

HCO3-

----------

-1

Sulphate

SO42-

----------

-2

Sulphite

SO32-

----------

-2

Sulphide

S2-

----------

-2

Nitrate

NO3-

----------

-1

Nitrite

NO2-

----------

-1

Nitride

N3-

----------

-3

Phosphate

PO43-

----------

-3

Phosphite

PO33-

----------

-3

Phosphide

P3-

----------

-3

Chlorate

ClO3-

----------

-1

Permanganate

MnO4-

----------

-1

Manganate

MnO42-

----------

-2

Dichromate

Cr2O72-

----------

-2

Chromate

CrO42-

----------

-2

Carbonate

CO32-

----------

-2

Oxalate

C2O42-

 

-2

Oxide

O2-

----------

 

Phosphorous

P4

4

 

Sulphur

S8

8

M.Mass=256 u

Ozone

O3

3

 

Dioxygen

O2

2

 

Helium

He

1

 

 

 

Formula Designing of Ionic Compounds:: Ionic compounds are those whose constituent particles are ions held together by strong electrostatic forces.

 

Name of compound

Cationic Part

Anonic Part

Mol.Formula (tool criss cross method)

Aluminiumsulphate

Al3+

SO42-

Al2(SO4)3

Feronssulphide

Fe2+

S2-

Fe2S2=FeS

Potasium chromate

K+

Cro42-

K2CrO4

Ammonium sulphate

NH4+

SO42-

(NH4)2SO4

Lead nitrate

Pb2+

NO3-

Pb(NO3)2

Potassium Dichromate

K+

Cr2O72-

K2Cr2O7

 

 

Molecular Formula/ Empirical formula:-

Molecular Formula :: It is the formula which represents the actual no. of atoms of various elements present in one molecule of the compound.

Empirical formula  ::  It is the formula which represents the simplest whole no. ratio of atoms of various elements present in one molecule of the compound.

 

Compounds

MF        

EF

Hydrogen Peroxide

H2O2

HO

Oxalic acid(Anhydrous)

H2C2O4

HCO2

 

 

DAY 2   2016-17

Objective ::  Mole Concept and  concept of concentration of solution.

 

Term

Numeral Representation

 One Pair

One Dozen

1 Mole

02

12

6.022x1023

 

1 mole = 6.022x1023 identical particles or entities =molar mass=22.4 L in case of gas at NTP

For example

I mole water= 6.022x1023 water molecules = 18 g water

I mole CO2 = 6.022x1023 CO2 molecules = 44 g CO2  =22.4 L CO2 at NTP

Mole (n) =   

 

unit of molar mass is g/mol 

  Note : unit of molecular mass is u and one u is equal to one g/molEg- 44 u = 44 g/mol

 

Solution (Binary):-It is a homogeneous mixture of two components whose composition may vary.

Solution = solute + solvent ( Component in bulk)

Concentration of solution.

Concentration of solution = Amount of solute/Amount of solvent/solution

 

Units of concentration :-

Mass % (w/W) =   

 

Mass % (w/V) =   

 

Molality (m) =   

 

Molarity  (M) =   

 

Strength =  Molarity  X Molar mass 

 

Unit of strength = g/L

 

Normality  = Molarity   X n factor

Species

n factor

Acid      

No of replaceable H+ ions

Base     

No of replaceable OH- ions

Ion        

No of charge

Oxidising agent/ Reducing                         

Change in oxidation No.

 

 

 

 

Dilution Law    M1V1=  M2V2

 

10 %  w/W means 10 g of solute in 100 g of solution

 

Density  =  Mass/ Volume

 

Problem :  Calculate the molality and molarity of 10 % w/W glucose solution if the density of solution is 1.2 g/ml.( Molar mass of Glucose = 180 g/mol)

 

Solution : 10 % w/W means 10 g  of solute present in 100 g of solution.

Mass of solute= 10g

Mass of solvent =90 g

Mass of solution =100g

Volume of solution =   

 

Volume of solution =   

 

Volume of solution =      L

 

Volume of solution =      L

 

Moles of solute  =   

 

Moles of solute  =   

 

Moles of solute  = 0.055

 

Molarity  (M) =   

 

Molarity  (M) =   

 

Molarity  (M) =   

 

Molarity  (M)  = 0.66 M

 

Molality (m) =   

 

Molality (m) =   

 

Molality (m) =   

 

Molality (m) = 0.61 m

 

Note :: Molality is better than molarity to express the concentration as it is temperature independent.

 

Problem :: How much water should be added in 200 ml of  5 M solution to prepare 2 M solution ?

Solution::

 

Milli moles before dilution = Milli moles after dilution

 

M1V1=  M2V2

 

5 X 200 = 2  X V2

 

V2 = 500 ml

 

Amount of added water = 500- 200 = 300 ml

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