Q6(a). Thermal decomposition of calcium oxalate
A thermogram was recorded for calcium oxalate monohydrate, CaC₂O₄·H₂O. The original sample weighed 24.60 mg and was heated from room temperature to 1000 °C at a rate of 5 °C/min. The following changes in mass and corresponding temperature ranges were observed: loss of 3.03 mg from 100–250 °C; loss of 4.72 mg from 400–500 °C; loss of 7.41 mg from 700–850 °C. Determine the solid residue at each step of the thermal decomposition.
Answer in brief
The successive solid residues are CaC₂O₄ (21.57 mg), CaCO₃ (16.85 mg) and CaO (9.44 mg).
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Coversthermogravimetric analysisTGAcalcium oxalate monohydratethermogramthermal decomposition
All parts of Question 6
- 6(a) Thermal decomposition of calcium oxalate15 marks
- 6(b) Organic precipitating reagents5 marks
- 6(c)(i) Lanthanoid–EDTA formation enthalpy5 marks
- 6(c)(ii) Non-stoichiometry of f-block oxides5 marks