How are thermograms obtained? What are the factors that
influence a thermogram? Draw the thermogram of calcium
oxalate monohydrate and explain the various features of the
diagram.?
Answers
Answer:
The principle of TGA and its applications:
TGA is thermogravimetric analysis.
It is one of the thermal method of analysis. (Thermal methods of analysis are based on the dynamic
relationship between temperature with a change in physical property like mass change or enthalpy change
etc)
In TGA mass of the substance is continuously monitored as the temperature is linearly increased.
TGA apparatus is used to measure TGA. It can scan over a wide range of temperature (25 – 1200 ⁰C)
The main components of TGA apparatus
1. A high precision thermobalence (± 10 μg)
2. Furnace with temperature programming facility.
3. Facility for providing inert atmosphere (like N2 gas) Or Oxidizing environment
4. A computer which can collect, store and process data – like plotting the graph.
The mass vs Temperature plot is called Thermogram. (an idealised thermogram is shown below)
Region I: The horizontal indicates the region where there is no mass
change. Ie from T1 to T2 the material is thermally stable.
Region II: The graph declines indicating a weight loss (weight loss can
be due to dehydration, decomposition, sublimation, desorption,
Evaporation etc. [Weight gain during Metal Oxidation, adsorption
etc]
Explanation:
Answer:
Influence the thermogram