When magnesium carbonate is heated

CHEMISTRY · Multi-part · A Level · Chemistry · Energetics · Energetics

Problem

When magnesium carbonate is heated, it decomposes according to MgCO3(s)⟶MgO(s)+CO2(g)\text{MgCO}_3(s)\longrightarrow \text{MgO}(s)+\text{CO}_2(g) Use the following thermochemical equations, all measured at 298 K298\,\text{K}: (a) Determine the standard molar enthalpy change for the thermal decomposition of magnesium carbonate shown above. (b) Calculate the enthalpy change per gram of MgCO3\text{MgCO}_3 decomposed. Report your answer in kJ g−1\text{kJ}\,\text{g}^{-1} to three significant figures. (c) A laboratory procedure decomposes 25.0 g25.0\,\text{g} of MgCO3\text{MgCO}_3. Compute the quantity of heat that must be supplied, assuming the process occurs at constant pressure and the measured enthalpy change equals the value from part (a).

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