2 Ag3AsO4 + 11 Zn + 11 H2SO4 → 6 Ag + 2 AsH3 + 11 ZnSO4 + 8 H2O
This is an oxidation-reduction (redox) reaction:
2 AsV + 16 e- → 2 As-III (reduction)
11 Zn0 - 22 e- → 11 ZnII (oxidation)
6 AgI + 6 e- → 6 Ag0 (reduction)
Ag3AsO4 is an oxidizing agent, Zn is a reducing agent, Ag3AsO4 is an oxidizing agent.