Select The Pair Of Substances Which Is NOT A Conjugate Acid-Base Pair. OANH And NH3 B. C6H5COOH And CoHs COO CH3Oand OH D. HOBr And OB E. S2- And HS
The Correct Answer and Explanation is :
The correct answer is B. C6H5COOH and C6H5COO-.
Explanation:
A conjugate acid-base pair consists of two substances related by the loss or gain of a proton (H+). In other words, an acid and its conjugate base differ by a single proton, and a base and its conjugate acid also differ by a single proton.
Let’s examine each pair:
- OANH and NH3:
- This pair is a conjugate acid-base pair.
- OANH (presumably an acid form of an organic compound) could donate a proton to become NH3 (ammonia), which is a base. When the acid loses a proton, it forms its conjugate base, NH3.
- C6H5COOH and C6H5COO-:
- This pair is a conjugate acid-base pair.
- C6H5COOH (benzoic acid) can donate a proton (H+) to become C6H5COO- (benzoate), the conjugate base. The proton is transferred from the acid to form the base.
- CH3O- and OH-:
- This is NOT a conjugate acid-base pair.
- CH3O- (methoxide ion) is the conjugate base of CH3OH (methanol), while OH- (hydroxide ion) is the conjugate base of water (H2O). These two are not related by a proton transfer, so they do not form a conjugate pair.
- HOBr and OBr-:
- This is a conjugate acid-base pair.
- HOBr (hypobromous acid) can lose a proton to form OBr- (hypobromite ion), which is its conjugate base.
- S2- and HS-:
- This is a conjugate acid-base pair.
- S2- (sulfide ion) is the conjugate base of HS- (hydrosulfide ion). HS- can donate a proton to form S2-, making them a conjugate acid-base pair.
Thus, Option C (CH3O- and OH-) is the only one that does not represent a conjugate acid-base pair.