The property measured in derivative thermogravimetric analysis (DTG) is :
Rate of change in weight
In ordinary thermogravimetric analysis (TG) the sample's mass is recorded as the temperature is raised, so the plot is mass against temperature and each decomposition step appears as a downward step in the curve.
Derivative thermogravimetry (DTG) plots the first derivative of that curve, \(\frac{dW}{dT}\) (or \(\frac{dW}{dt}\)), against temperature. The quantity measured is therefore the rate of change in weight, not the weight itself.
The practical value of taking the derivative is resolution. A step in the TG curve becomes a peak in the DTG curve, and two decomposition steps that overlap into one sloping shoulder on the TG trace resolve into two distinguishable peaks on the DTG trace. The peak maximum gives the temperature of fastest mass loss, and the peak area is proportional to the total mass lost in that step.
Change in weight is what plain TG measures, so it describes the parent technique rather than its derivative form.
Heat evolved is measured by differential scanning calorimetry (DSC) or differential thermal analysis (DTA), which follow enthalpy changes rather than mass.
Change in temperature is the independent variable that is scanned in all of these methods, not the measured response.
Hence DTG measures the rate of change in weight.
Similar Questions
Analysis of four different samples of an alloy yielded 12.12, 12.14, 12.10 and 12.22% of metal. The mean deviation of the result is :
For the first order consecutive reaction :
Which of the following statement is incorrect ?
A given reaction is fitted into the following Arrhenius form :
K2 = 6.0 × 1014 (S-1) . exp \(\left[-\frac{104.4\ (\mathrm{kJ\,mol^{-1}})}{RT}\right]\)
Value of the rate constant at very high temperature would be :
E° value for various ions are as follows :
E°(MnO4-) = +1.51 V
E°(Ag/Ag+) = +0.7996 V
E°(Au/Au+) = +1.692 V
E°(Zn/Zn2+) = -0.761 V
Based on this data, permaganate can be used to oxidize :
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The following half cell represents, normal hydrogen electrode (NHE) :
If, we discharge the electrochemical cell rapidly, then :
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H2S(g) + \(\tfrac{3}{2}\) O2(g) → SO2(g) + H2O(g), ΔH° = 518.62 kJ
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Important Questions from Thermodynamics
- Second law of thermodynamics states that
A. Energy flows from higher concentration to lower concentration.
B. Order becomes disorder during energy transformations.
C. The quality of energy degrades as it is transformed.
D. Degraded energy is entropy, dessipated as waste products or heat.
E. Enthalpy is wasted in energy transformation.
Choose the most appropriate answer from the options given below: Choose the Incorrect Statement:
1 For a system at equilibrium, chemical potential is same in all phases.
2 Gibb's free energy change is zero at equilibrium state of a system.
3 Gibb's free energy change is positive for reaction to occur spontaneously.
4 $\Delta G$ will become more negative with increasing temperature.- In a closed thermodynamic system, across its boundaries
Melting Point of pure ice is-
Which one among the following statements with reference to the properties of water is not correct?
