Hydrogen gas is passed through an electric arc struck between tungsten electrodes at 4000 K, creatin — Hydrogen Chemistry Question

💡 Solution & Explanation

The electric arc dissociates molecular $H_2$ into atomic hydrogen. Because the $H-H$ bond enthalpy is massively high ($435.9\text{ kJ mol}^{-1}$), the recombination of these atoms on a metal surface is intensely exothermic, generating temperatures around 4000 K used in atomic hydrogen welding torches.