Hey Taylor! Did you happen to miss an Oxygen on the product side? There is no way to balance this reaction without the second Oxygen. Check the question and let us know!
Hey, unfortunately no, I copied the exact question from Mastering Chemistry.
Okay Taylor. Here is the solution. In the end, notice that 1 Cu gives you 2 e- to form 1 Cu2+. 2H2O (O in -2 oxidation state) can form 2OH- (O in -2 oxidation state) + 2H+
O2 (O in 0 oxidation state) combine with 2H+ to form 2OH- by gaining 4e-, thus, overall we need 4e- from Cu(s). Hope this makes sense!