Add uworld tag for Q 403504 bc:"Reaction 2 , which species is the conjugate base in the forward reaction? [M(H2O)5OH](n − 1)+(aq) (75%)
The conjugate of an acid (or base) is the species that the acid (or base) becomes after losing (or gaining) one proton (ie, an H+ ion). A base is converted into its conjugate acid when the base accepts a proton. Likewise, an acid is converted into its conjugate base when the acid donates a proton. Therefore, an acid (or base) and its conjugate have chemical formulas that differ by only one proton.
In the forward direction of Reaction 2, the [M(H2O)6]n+(aq) complex acts as an acid by donating a proton to a H2O(l) molecule. Therefore, [M(H2O)5OH](n − 1)+(aq) is the conjugate base of the acid in the forward reaction (ie, the species that the [M(H2O)6]n+(aq) acid becomes after losing one proton).
(Choice A) [M(H2O)6]n+(aq) acts as the acid in the forward direction of Reaction 2.
(Choice B) H2O(l) acts as the base in the forward direction of Reaction 2, but this is not

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