- Leveling effect (chemistry)
HA + H2O -> A- + H3O+
Any acid that is stronger than H3O+ reacts with H2O to form H3O+; therefore, no acid can be stronger than H3O+ in H2O.
This is true with any solvent, although usually to a lesser extent than with water. Bases may be also leveled in solvents.
H-O-H + NH2- --> H-O- + NH3
(Stronger Acid) (Stronger Base) --> (Weaker Base) (Weaker Acid)
Leveling and differentiating solvents
A weakly basic solvent has less tendency than a strongly basic one to accept a proton. Similarly a weak acid has less tendency to donate protons than a strong acid. As a result a strong acid such as perchloric acid exhibits more strongly acidic properties than a weak acid such as acetic acid when dissolved in a weakly basic solvent. On the other hand, all acids tend to become indistinguishable in strength when dissolved in strongly basic solvents owing to the greater affinity of strong bases for protons. This is called the leveling effect. Strong bases are leveling solvents for acids, weak bases are differentiating solvents for acids.
To use bases stronger than the hydroxide ion, use a solvent that is a weaker acid than water.
To use acids stronger than the hydroxonium ion, use a solvent that is a stronger acid than water.
- ^ Solomons & Fryhle's Organic Chemistry (8th Ed.)
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