Problem of the week: 18 March 2023

This week’s question is one from the 2023 edition of the Chemistry Race, and is a particularly satisfying one to solve, without being too difficult!

Thermogravimetric analysis (TGA) is an analytical method for investigating temperature-dependent phase transitions and chemical reactions of solid compounds. In this protocol, the mass of the sample is measured as the percentage of original mass over time as the temperature changes.

Consider the oxalate salt of metal M. Its monohydrate salt (MC2O4·H2O) was analyzed using TGA and the result is shown in the following thermogram, showing three stages of reactions, where A, B and C are solid products of each stage. By deducing the identity of M, give the molecular formulae for A, B and C.

Credit: Chemistry Race, Anh Phung


A: CaC2O4, B: CaCO3, C: CaO

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