code: def dissolved(self, concs):
          
          new_concs = concs.copy()
          for r in self.rxns:
              if r.has_precipitates(self.substances):
                  net_stoich = np.asarray(r.net_stoich(self.substances))
                  s_net, s_stoich, s_idx = r.precipitate_stoich(self.substances)
                  new_concs -= new_concs[s_idx]/s_stoich * net_stoich
          return new_concs
docs: Return dissolved concentrations