Calculate the standard Gibbs energy of reaction for the following: Cu2S (s) + O2 (g) -> 2 Cu (s) + SO2 (g) using the following information. Cu2S (s) -> 2 Cu (s) + S (s) has a standard Gibbs energy of reaction of 86.2 kJ/mol and S (s) + O2 (g) -> SO2 (g) has a standard Gibbs energy of reaction of -300.1 kJ/mol.