In tables, all reaction are reduction reactions
For H : 2 H+ + 2 e- -> H2 E = 0 V (definition)
In first reaction H oxidized, and E = 0 V
Then find E for reaction F2 + 2e -> 2 F-
calculate sum together
In next reaction Copper is reduced and Ca oxidized
Find E for reactions Cu2+ + 2e- -> Cu
Ca2+ + 2e- -> Ca
Because lower reaction happens from right to left,
