Separate the redox reaction into its component half‑reactions. O2+4Cu⟶2Cu2O

Use the symbol e− for an electron.

I found the
Oxidation half reaction: Cu ---> Cu^+ + e^-
Reduction half reaction: O2 +4e^- > 2O^2-

The reactions shown here can be combined to make the overall reaction c(s) + h2o(g) ⇌ co(g) + h2(g) by reversing some and/or dividing all the coefficients by a number. a. c(s) + o2(g) → co2(g) k=1.363×10^69 b. 2 h2(g) + o2(g) → 2 h2o(g) k=1.389×10^80 c. 2co(g) + o2 (g) → 2 co2(g) k=1.477×10^90