1. Techniques of Volumetric Analysis
SMKN 13 Bandung

2. Objectives After this session, the students are expected to be able :
To explain analysis of volumetric
To explain reactant for analysis of volumetric
To explain steps of techniques of volumetric analysis
To explain calculation in volumetric analysis
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3. Introduction
Volumetric analysis is the process for determining the amount in the solution
Can be achieved by accurately measuring volumes and concentration
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4. Standard Solution
Standard solution is one in which the concentration of all solute species is accurately known
Standard solution can be prepared in two ways:
1. Directly from a primary standard
2. By standardization
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5. Primary standard substance
Criteria for primary standard :
1. It must be obtainable in a high state of purity and have a known formula
2. It should be easily stored and without reacting with the atmosphere
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6. Primary standard substance
3. It should be readily available and relatively inexpensive
4. It should have a reasonably high formula weight to minimize errors in weighing
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7. Primary standard substance
5. For example :
sodium oxalate (Na2C2O4)
sodium carbonate (Na2CO3)
sodium tetra borate
(Na2B4O7.10 H2O)
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8. Secondary standard substance
Secondary standard substances are of a lower degree of purity than the primary ones
The concentration of the active agent of a secondary standard substance is found by comparison against a primary standard or by the use of a suitable analytical method of known accuracy
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9. Secondary standard substance
Secondary substances are frequently used in practice; they must be kept under condition such that their composition does not change
For example :
KMnO4 ; HCl ; H2SO4 ; HNO3; NaOH
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10. Titration
A titration is the process in which a solution of one reactant (A) is added from a burette to a fixed volume, measured by pipette, of a solution of the other reactant (B)
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11. End Point and Equivalence Point
Definition
End point : the point at which the colour of indicator is change
Equivalence point : the point where chemically equivalent amount of each reactant, according to the equation for the reaction are present
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12. Steps of techniques volumetric analysis
Weighing sample
Diluting sample into volumetric flask
Transfer by volumetric pipette from volumetric flask into Erlenmeyer flask
Add a few drops of indicator and then titrated from burette until the colour change
Do the titration until the volume required is constant (the difference between two titration not more than 0.02 mL)
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13. Steps of techniques volumetric analysis
5. Do the titration until the volume required is constant (the difference between two titration not more than 0.02 mL)
6. Calculate the data (as concentration) and report it
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14. Standarization of HCl Using * primary standard :
sodium carbonate (Na2 CO3)
* Indicator : methyl red
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15. Standarization of HCl
A solution of approximately 0.1 M HCl was standardized using sodium carbonate
1.325 g of Na2 CO3 was dissolved in a little water in a 250 mL of volumetric flask and the solution made up to the mark with water
After thorough mixing, 25 mL of the Na2 CO3 solution was pipetted into a 250 mL of Erlenmeyer flask, add several drops of methyl red
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16. Standarization of HCl
The HCl solution was slowly added from a burette until the colour change from yellow to reddish-orange
The volume was mL. What was the concentration of the HCl solution?
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17. The equation for the reaction is
2 HCl (aq) + Na2CO3 (aq) NaCl (aq) +CO2 (g) +H2O(l)
The relative formula mass of Na2 CO3 = 106
Volume of Na2CO3 solution = 250 mL
n(Na2CO3) = mol
= mol
In 25 mL of Na2CO3 solution,
n(Na2CO3) = x mol
= mol
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18. Standarization of HCl
From equation representing the reaction of HCl and Na2CO3,
n(HCl) = 2 x n(Na2CO3)
= 2 x mol
= mol
Using , it can be seen that
c(HCl) =
= M
The concentration of the HCl solution is M
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