Even though so much energy is required to form a metal cation with a 2+ charge, the alkaline earth metals form halides with the general formula MX2, rather than MX. (a) Use the following data to calculate of MgCl: Page 403 (b) Is MgCl favored energetically relative to Mg and Cl2? Explain. (c) Use Hess’s law to calculate ΔH° for the conversion of MgCl to MgCl2 and Mg ( of MgCl2 = −641.6 kJ/mol). (d) Is MgCl favored energetically relative to MgCl2? Explain.