Thermogravimetry is the technique in which change in the weight is recorded as the function of temperature Or time. The phenomenon is used for qualitative as well as quantitative analysis.
The following are the factors:
1) Heating Rate: When the substance is heated to the faster rate, the temperature of the sample (decomposition) is higher, it means temperature changes and as thermogram depends on temperature so the thermogram changes.
2) Heat of Reaction: It depends whether the reaction is exothermic or endothermic, it means heat changes so the thermogram changes.
3) Furnace Atmosphere: The nature of the surrounding atmosphere can have the effect on temperature of decomposition. e.g. instead of N2 if CO2 is used as surrounding atmosphere, the decomposition of CaCO3 take place at much higher temperature. $$ CaC{ O }_{ 3 }\quad \overset { \Delta }{ \longrightarrow } \quad CaO\quad +\quad C{ O }_{ 2 } $$ As the CO2 is on R.H.S. so the reverse reaction takes place, so the nature of thermogram changes. It means whenever furnace atmosphere is enrich with one of the product of reaction the decomposition temp. changes and so the nature of thermogram changes
4) Geometry of Crucible: The geometry of crucible can change slope of TGA curve, usually flat shaped crucible is used, because the diffusion of gases evolved is easier.
5) Characteristics of Samples: Characteristic means amount of sample, particle size packing density, thermal conductivity of sample, the mode of preparation of sample and the atmosphere around it.
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