1. Concept of volumetry

2. CHEMICAL ANALYSIS METHODS OF CHEMICAL ANALYSIS Volumetry Gravimetry Chromatography Atomic absorption spectrometry Potentiometry Spectrophotometry Conductometry Turbidimetry Nephalometry Thermometry Radiometry Argentometry Acidimetry Alkalimetry Chemical analysis is the resolution of achemical compounds into its proximate or ultimate parts

3. TYPES OF CHEMICAL ANALYSIS: Quantitative Analysis Qualitative analysis It is to ascertain the species of elements present in an unknown sample Eg: Copper sulphate, Sodium chloride. Quantitative analysis It is to determine how much of each component or specified component present in an unknown sample. Eg: i) Cu and SO 4 each. ii) Na and Cl.

4. CLASSICAL METHODS OF QUANTITATIVE ANALYSIS Volumetric analysis Gravimetric analysis Volume try is the part of the quantitative analysis. It is also called as ‘Titrimetry’ Volumetry – Volumetry is the accurate measurement of volume of solution of known concentration which is needed to react quantitatively with the solution of the substance to be determined

5. VOLUMETRIC EXPERIMENT i) Standard Solution ii) Unknown standard solution iii) Indicators

6. STANDARD SOLUTION Standard solution is one whose concentration or strength is accurately known. It is also called as “titrant” Whereas unknown standard solution is the one whose concentration is not accurately known and which is also known as “analyte” Process of adding a standard solution from a volumetric burette to a solution of the unknown concentration in the conical flask until the reaction is just complete is known as “Titration” The completion of chemical reaction is referred to as titration “end point” The end point or equivalent point of titration is recognized by the chemical reagent called “Indicator”

7. PREPARATION OF STANDARD SOLUTIONS Standard solutions are prepared by dissolving an accurately weighed quantity of the standard chemical (AR/GR) substances and making up the solution to a definite volume Eg. Dissolve 5.30 gm Sodium carbonate (Na 2 CO 3 ) (AR) in 100 ml D/W to get 0.1 N. Na 2 CO 3 solution A substance of 100% pure and stable is called primary standard substance

8. REQUIREMENTS OF A PRIMARY STANDARD SUBSTANCE – It must be 100% pure and dry. – It must be 100% soluble in suitable solvent. – It should not be hygroscopic. – It should get oxidized by oxygen or affected by CO 2 – The reactions should be stoichimetric and instantaneous. EXAMPLES OF STANDARD SUBSTANCES Sodium carbonate, Pot. dichromate, Pot. bromated, Sod. Oxdate, Pot. iodide, Arsenius oxide, Oxalic acid etc.,

9. SECONDARY STANDARD SUBSTANCES A chemical substance is one which is not 100% pure and unstable and whose concentration can be exactly determined by standardizing against a primary standard solution by following titration procedure Eg: (i) Sodium hydroxide (0.1N) by standard Sulphuric acid (ii) Sodium thiosulphate by Pot.iodate / Pot. dichromate

10. PRECAUTION & STANDARD SOLUTIONS The standard solutions must be kept in a clean reagent bottle The solution must be protected from atmospheric gases, light, temperature, etc Potassium permanganate (KMNO 4 ) and sliver nitrate (AgNO 3 ) solutions must be preserved in dark reagent bottles Some chemicals should keep in refrigeration. Eg: Ammoninum molybdate, Starch, EDTA solution, Sulphanilamide, etc

11. DILUTE SOLUTIONS, THEIR UNITS AND CONCENTRATIONS Chemical solutions are prepared by dissolving substances in solution depending on their dissolving properties of chemical substances The concentration of the solution is expressed as: – Normal solution (N) – Molar Solution (M) – Molal solution (m) – Formal solution (F)

12. Normal Solution (N) A normal solution contains one gram equivalent mass of the substance in one liter of solution. Mass of the substance in one liter Normality = ------------------------------------------------ Gram equivalent mass of the substance Eg: 1.0 N HCL solution contains 36.45 gm of HCl in one litre of d/w

13. Equivalent Mass The equivalent mass of a substance is that mass which is chemically equivalent to one atom of hydrogen or half a gram atom of oxygen or 1.0 g atom of chlorine The relation between molecular mass and equivalent mass of a substance is Molecular Mass Eq. Mass = ---------------------------------------- n Where ‘n’ corresponds to the number of gm atoms of hydrogen or half a gram atom of oxygen or 4 gm of chlorine

14. Eg: 1) Equivalent of an acid: a) HC1 has one replaceable H + atom Mol. Mass Eq. Mass of HCl = ---------------------------- N = 36.45 N = 36.45 = 36.45 1

15. b) H 2 SO 4 has 2 replaceable H + atoms 89 Therefore Eq mass of H 2 SO 4 = ------------------------ = 49 2 Eg. 2) Equivalent of a base a. NaOH + HCl NaCl + H 2 O, ( NaOH = 1 H +) Eg. Mass of NaOH = 40 = 40 1 b. Ba (OH) 2 +2HCl BaCl 2 +2H 2 O, ( Ba (OH) 2 =2H +) Eq. mass of Ba (OH) 2 = 171.36 = 85.68 2

16. Eg.3) Equivalent of an oxidizing or reducing agents a. 2KMnO 4 +2H 2 SO 4 K 2 SO 4 +2MnSO 4 +3H 2 O+5(O) ( KMnO 4 = 5 (O)) Eg, Mass of KMnO 4 = 158 = 31.6 5 b. FeSO 4 + H 2 SO 4 + (O) Fe 2 (SO 4 ) 3 + H 2 O ( FeSO 4 = 1(O)) Eg, mass of FeSO 4 = 152 =152 1 Eg.4) Substances reacting with AgNO 3 of halogens AgNO 3 + KCl AgCl + KN0 3 AgNO 3 Ag + + Cl - Eg. Mass of AgNO 3 = 170 = 170 1

17. II Molar Solution (M) A solution said to be 1.0 molar (M) if it contains one mole of the substance in 1000ml of D/W Eg. 1.0 Molar HCl consists of 36.5gm HCl in 1000ml of distilled water III. Moral solution (m) A solution said to be one moral (1.0 m) if it contains one mole of the substance in 1000gms of the solvent Eg. 1.0 Moral H 2 SO 4 solution contains 98gm of H 2 SO 4 in 1000ml of water

18. IV. Formal solution (F) A solution is said to be one formal (1.0F) if it contains one formula mass of the substance in one liter of solution Eg. I.0F solution of Oxalic acid (H 2 C 2 O 4, 2H 2 O) contains 126gm. Oxalic acid in one liter of solutions

19. Percentage of Solution 1. Weight composition percentage (W/V ratio) Eg: 2% NaCl solution means that 2.0gm of NaCl crystals dissolved in 100ml of d/w 2. Volume composition percentage. (V/V ratio) Eg. 20% Alcohol solution means that 20ml of alcohol mixed with 80ml of d/w Note: Volume percentage is used when two liquids are mixed to form solution. It is the ratio of volumes of liquids.