Gravimetric analysis is an analytical method that determines the quantity of analyte by measuring the mass of a substance containing it, involving steps such as preparation, precipitation, digestion, filtration, washing, drying, and weighing. The method can be divided into two types: precipitation and volatilization, with advantages including higher accuracy and precision compared to volumetric methods, but also disadvantages such as being time-consuming and susceptible to coprecipitation errors. Key examples include the determination of calcium through precipitation of calcium oxalate and the separation of water through volatilization.

1. Presented by Ayush Koul (19103083)
Gravimetric Analysis
Aircraft Materials - ASC4251

2. Content
Introduction
Steps Involved In Gravimetric Analysis
Types of Gravimetric Analysis
Examples
Advantages / Disadvantages

3. Introduction
Gravimetric Analysis is a group of analytical methods in
which the amount of analyte is determined by the
measurement of the mass of a pure substance containing
the analyte.
It is and ABSOLUTE method.

4. Steps Involved In Analysis
Preparation of the solution.
Precipitation.
Digestion.
Filtration.
Washing.
Drying / Ignition.
Weighing.
Calculation.
1.
2.
3.
4.
5.
6.
7.
8.

5. STEPS

6. We may need preliminary separation to separate potential
interferences before precipitating analyte.
Adjustment of solution condition .
Most of the substances are readily solute in water and can be used
as such.
for ex - (pH/temp/vol/concentration of test substance).
Preparation of the solution.
1.

7. The precipitating reagent is added at a concentration that
favors the formation of a "good" precipitate.
This may require low concentration, extensive heating or
careful control of the pH.
A large excess of precipitant should be avoided because this
increases chances of adsorption on precipitate.
No new ppt should be formed after addition of drop of
ppting agent.
2. Precipitation.

8. Let precipitate stand in contact with the
solution from which it was precipitated usually
at high temperature.
The small particles tend to dissolve and
precipitate on the surfaces of the larger
crystals. This process is called digestion.
3. Digestion.

9. 4. Filtration.
Precipitate is separated from it's mother solution.
Filtration medium used are:-
i ) Filter papers
ii) Filter pulps
iii) Filter mats
iv) Crucible fitted with porous plate (Sintered glass filters)

10. 5. Washing.
Co precipitated impurities especially those on surface, removed by
washing the precipitate .
For example - HNO3 for AgCl.

11. 6. Drying or Ignition.
To remove solvent and wash electrolytes it is heated at 110 to 120°C
for 1 to 2 hrs.

12. 7. Weighing.
After the precipitate is allowed to cool it is weighed (in the crucible).
It is Properly calibrated analytical balance instrument.
Advanced and good weighing technique.

13. Types Of Gravimetric Analysis
Precipitation
Volatilization
There are two main types of gravimetric analysis: -
1.
2.

14. Calcium can be determined gravimetrically by precipitation of
calcium oxalate and ignition of the oxalate ion to calcium oxide.
The precipitate thus obtained are weighed and the mass of calcium
oxide is determined.
Example for Precipitation

15. Example of volatilization
Water can be separated from most inorganic compounds by ignition,
the evolved water can then be absorbed .
The weight of water evolved may be calculated from the gain in
weight of the absorbent.

16. Advantages And Disadvantages
Advantages -
Accurate and precise.
Gravimetric analysis is potentially more accurate and more precise
than volumetric analysis.
Possible sources of errors can be checked.
Gravimetric analysis avoids problems with temperature
fluctuations, calibration errors, and other problems associated with
volumetric analysis.
1.

17. Advantages And Disadvantages
Proper lab technique is critical.
Time consuming.
Coprecipitation is a major drawback.
2. Disadvantages: -

18. Thank You