2 Ca + (COO)2Na2 → (COO)2Ca2 + 2 Na
This is an oxidation-reduction (redox) reaction:
2 CIII + 2 e- → 2 CII (reduction)
2 NaI + 2 e- → 2 Na0 (reduction)
2 Ca0 - 4 e- → 2 CaII (oxidation)
(COO)2Na2 is an oxidizing agent, (COO)2Na2 is an oxidizing agent, Ca is a reducing agent.