Answer
$H_3AsO_4(aq) + H_2O(l) \lt -- \gt H_2As{O_4}^-(aq) + H_3O^+(aq)$
$H_2As{O_4}^-(aq) + H_2O(l) \lt -- \gt HAs{O_4}^{2-}(aq) + H_3O^+(aq)$
$HAs{O_4}^{2-}(aq) + H_2O(l) \lt -- \gt As{O_4}^{3-}(aq) + H_3O^+(aq)$
Work Step by Step
1. Identify if the compound is a polyprotic acid or base:
- $H_3AsO_4$ is an acid.
2. Write the ionization equation for the original acid.
- Write an equation where $H_3AsO_4$ donates a proton to a water molecule.
3. Now, for polyprotic acids, the conjugate base is capable of donating one proton too, so write an equation where it does that.
- $H_2As{O_4}^-$ can act as an acid too, so write an equation where it donates a proton to a water molecule.
- Repeat "Step 3" for the next reaction, until the conjugate base is incapable of donating one proton.
