The esterification of acetic anhydride by ethyl alcohol can be represented by the following balanced equation:
`underset(A)((CH_(3)CO)_(2)O) + underset(B)(C_(2)H_(5)OH) rarrCH_(3)COOC_(2)H_(5) + CH_(3)COOH`
When the reaction is carried out in dilute hexane solution, the rate may be represented by `k[a][b]`. When ethyl alcohol `(B)` is the solvent, the rate may be represented by `k[A]` the values of `k` are not the same in the two cases). Explain the difference in the apparent order of the reaction.

Explanation

When a solvent is also a reactant, its concentration is so large compared with the extent of reaction that it does bot change. (Compare the convention we used, in studying the thermofynamics of aqueous solutions, of viewing water as always being in its standard state in all dilute solutions). Thus, the dependence of the rate on the concentration of ethyl alcohol cannot be determined unless ethyl alcohol becomes a solute in some other solvent so that its concentration can be varied.