... do not convincingly demonstrate that an equilibrium is occurring; even at 4 M benzene, where the solution is ∼ 40% benzene by volume, more than ... of e - s to (e - s ,Na + ) observed is expected on the basis of dissociation constants K d (NaBΦ 4 ) = 8.52 × 10 -5 M -1 33 and the ...