Complete the equation for the thermal decomposition of $\text{MgC}_2\text{O}_4$. $\text{MgC}_2\text{O}_4 \rightarrow$
Suggest which of $\text{MgC}_2\text{O}_4$ or $\text{CaC}_2\text{O}_4$ decomposes thermally at the lower temperature. Explain your reasoning.
The ethanedioate ion is oxidised by acidified $\text{KMnO}_4$. $5\text{C}_2\text{O}_4^{2-} + 2\text{MnO}_4^- + 16\text{H}^+ \rightarrow 10\text{CO}_2 + 2\text{Mn}^{2+} + 8\text{H}_2\text{O}$ An experiment is carried out to determine the solubility of $\text{MgC}_2\text{O}_4$ in water. A $40.0\,\text{cm}^3$ sample of saturated aqueous $\text{MgC}_2\text{O}_4$ needs $27.05\,\text{cm}^3$ of $0.00200\,\text{mol dm}^{-3}$ acidified $\text{KMnO}_4$ to oxidise all of the $\text{C}_2\text{O}_4^{2-}$ ions. Calculate the solubility, in $\text{mol dm}^{-3}$, of $\text{MgC}_2\text{O}_4$ in water. Show your working.