Q2(c). CaCO₃ and MgCO₃ in a dolomite sample from its thermogram
A dolomite sample is analyzed by thermogravimetry. Using the given data, determine the concentration of CaCO₃ and MgCO₃ (in wt%) in the dolomite sample. (Y-axis not in scale) [Thermogram given in the paper: mass marks 60.0, 33.4, 29.0 and 18.0 mg; temperature marks 200, 470, 650 and 850 °C.] Given: atomic mass of Ca, Mg, C and O are 40, 24, 12 and 16, respectively.
Model answer
The free solution for 2023 answers questions 1, 4, 5, 6, 7 and 10, the ones picked in its time plan. Question 2 is answered in full in the Geo-Scientist Chemistry Paper III, 2021 to 2025 book, with every part of every paper.
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UPSC Combined Geo-Scientist (Main) Chemistry Paper III: Model Answers 2021 to 2025
- All ten questions of each paper, with the question printed above its answer
- Instruments drawn as labelled diagrams, numericals worked with units
- Topic-wise weightage and a topic-wise index
CoversthermogravimetrydolomiteCaCO3 MgCO3 decompositionthermogramTGA calculation
All parts of Question 2
- 2(a) Type of analysis: 1 µL sample, analyte at ppb to ppm5 marks
- 2(b) Number of theoretical plates and HETP from a Gaussian peak10 marks
- 2(c) CaCO₃ and MgCO₃ in a dolomite sample from its thermogram10 marks
- 2(d) No K lines of silver at a tube voltage of 24 kV5 marks