The surface of copper gets tarnished by the formation of

Last updated: 7/4/2023

The surface of copper gets tarnished by the formation of copper oxide N2 gas was passed to prevent the oxide formation during heating of copper at 1250 K However the N gas contains 1 mole of water vapour as impurity The water vapour oxidises copper as per the reaction given In PH PM 0 below 2Cu s H O g Cu O s H g PH is the minimum partial pressure of H in bar needed to prevent the oxidation at 1250 K The value of In PH is Given total pressure 1 bar R universal gas constant 8 J K 1 mol In 10 2 3 Cu s and Cu O s are mutually immiscible At 1250 K 2Cu s 2O2 g Cu O s AG 78 000 J mol 1 H2 g O2 g H O g AGe 1 78 000 J mol G is the Gibbs energy 2018