1. Dnyanasadhana College, Thane.
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Department of Chemistry T.Y.B.Sc. Analytical Chemistry Paper-IV Sem-VI
Thermogravimetric analysis
Dr.Bhagure G.R.

2. Contents
4.1.2 Thermogravimetric methods of analysis: Instrumentation basic components of thermobalance block diagram(balance,furnace, temperature measurement and control, recorder),
Thermogram (TG curve)Factors affecting TG curve
Instrumental factors (Furnace heating rate, furnace atmosphere ,geometry of the sample holder) and Sample characteristics (effect of sample mass, effect of sample particle size and effect of heat of reaction),
Applications of TGA TGA
of CaC2O4 .H2O and CuSO4.5H2O Determination
of Drying temperature range and ignition temperature.

3. Physical Changes Chemical Changes Substance Heated
Thermogravimetric analysis

4. Weight
No loss in weight
Loss in weight
Time / Temperature
Thermogram

5. TGA – Principle of Operation
Thermogravimetry (TG) determines the mass change of a sample as a function of temperature or time.
A good tool for:
Quality Control And Assurance
Failure Analysis Of Complex Polymer Mixtures And Blends.
Study of a variety of chemical processes accompanied by mass changes.

6. Thermal Methods of Analysis
Properties are measured as a function of temperature, time, or both
Heat flow – direction and magnitude
Mass change – loss / gain
Mechanical properties
Sheer
Strain
Dynamic loading
Gas evolution
CHM 342

7. INSTRUMENTATION:
The instrument used in thermogravimetry (TG) is called a thermobalance. It consists of several basic components in order to provide the flexibility necessary for the production of useful analytical data in the form of TGA Curve as shown in Fig.1.
Basic components of a typical thermobalance are listed below;
i) Balance
ii) Furnace: heating device
iii) Unit for temperature measurement and control (Programmer)
iv) Recorder: automatic recording unit for the mass and temperature changes
These components may be represented by simple block diagram as in Fig.2

8. INSTRUMENTATION Thermo balance Furnace: heating device Sample Holder
Recording Balance and Balance Control
Furnace: heating device
Furnace temperature Programmer
Sample Holder
Atmospheric Control
Recorder: automatic recording unit for the mass and temperature changes

9. Characteristic of good Thermobalance
Weight change of sample should be recorded continuously.
Furnace should reach maximum desired temperature.
Heating rate should be linear and reproducible
Sample holder should be in hot zone
Provision to vary the heating rate in furnace
Balance mechanism should be protected from furnace and corrosive gases.
Recording of tem and wt to an accuracy of 0.01g.
Balance should be sensitive

10. Factors affecting on Thermobalance Instrumental factors
Sample Characteristics

11. Sample holder Geometry
Instrumental factors
Heating rate
Furnanace
atmosphere
Static Air
Dynamic Air
Inert Atmosphere
Sample holder Geometry

12. Sample Characteristics
Weight of sample
Large amount sample
Small amount Sample
Particle size of sample
Smaller or greater particle size
Compactness of sample
Loose or compressed sample

13. Application of Thermogravimetry

14. Copper sulphate pentahydrate
Percentage
Wt.
Loss B
Temperature

15. Decomposition of Copper sulphate pentahydrate
Reaction
Temperature
CuS04.5H20CuS04.H H20 K
CuS04.H20 CuS04 +H20 K
CuS Cu0+ S02+1/2 02 K
2Cu  + Cu20+ ½ 02

16. Thermogravimetric Analysis (TGA)
A technique that permits the continuous weighing of a sample as a function of temperature and/or as a function of time at a desired temperature

17. Applications
To measure a property of interest, such as specific heat, latent heat or heat of reaction
To fingerprint a particular material or substance
To assess high temperature stability of materials
To detect phase transformations
Fundamental studies of reaction kinetics

18. TGA Applications: Inorganic

19. TGA Applications: Organics
Identification of polymers and pharmaceutical agents
Thermal stability of synthetic and natural polymers and other organics
Analysis of polymer-matrix composites
Kinetics and mechanism of solid organics – gas reactions
Residual solvent determinations

20. TGA Applications: Organics
Determination of purity and thermal stability of Primary and secondary standards used in titrimetry.
Determination of correct drying temperature of substance.
Determination of composition of complex mixtures.
Thermal decomposition of inorganic and Inorganic polymeric substances.
Solid state reactions
Roasting and calcining of minerals .
Identification of polymers and pharmaceutical agents
Thermal stability of synthetic and natural polymers and other organics
Analysis of polymer-matrix composites
Kinetics and mechanism of solid organics – gas reactions
Residual solvent determinations

21. THANK YOU