Hammett acidity function
E743330
The Hammett acidity function is a quantitative measure of superacidity in very strong acid solutions, extending the concept of pH to media where conventional acidity scales fail.
Statements (46)
| Predicate | Object |
|---|---|
| instanceOf |
acidity function
ⓘ
acidity scale ⓘ chemical concept ⓘ |
| abbreviation | H0 ⓘ |
| appliesTo |
concentrated sulfuric acid
ⓘ
fluoroantimonic acid NERFINISHED ⓘ magic acid NERFINISHED ⓘ non‑aqueous strongly acidic media ⓘ superacid solutions ⓘ |
| assumes | common activity coefficient for indicator base forms ⓘ |
| basedOn |
equilibrium of weak bases in acid media
ⓘ
indicator base ionization equilibria ⓘ |
| category |
acid–base property scale
ⓘ
thermodynamic acidity measure ⓘ |
| contrastsWith | activity‑based pH definition ⓘ |
| convention | more negative H0 indicates stronger acidity ⓘ |
| dependsOn |
concentration of protonated base
ⓘ
concentration of unprotonated base ⓘ pKBH+ of indicator base ⓘ |
| developedBy | Louis Plack Hammett NERFINISHED ⓘ |
| developedIn | 1930s ⓘ |
| extends | pH concept ⓘ |
| field |
acid–base chemistry
ⓘ
physical organic chemistry ⓘ |
| hasFormula | H0 = pKBH+ + log([B]/[BH+]) ⓘ |
| hasLimitation |
depends on choice of indicator base
ⓘ
may differ between different basic indicators in same medium ⓘ |
| measures |
acidity in very strong acid solutions
ⓘ
superacidity ⓘ |
| namedAfter | Louis Plack Hammett NERFINISHED ⓘ |
| relatedTo |
Brønsted acidity
ⓘ
Lewis acidity ⓘ acidity function H− ⓘ pH scale ⓘ |
| requires | series of indicator bases with known pKBH+ ⓘ |
| unit | dimensionless ⓘ |
| usedBy |
catalysis researchers
ⓘ
physical organic chemists ⓘ synthetic organic chemists ⓘ |
| usedFor |
characterizing acidity where pH is not defined
ⓘ
comparing strengths of superacids ⓘ quantifying protonating ability of superacids ⓘ |
| usedIn |
carbocation chemistry
ⓘ
electrophilic substitution studies ⓘ industrial superacid catalysis research ⓘ kinetic studies in superacid media ⓘ |
Referenced by (3)
Full triples — surface form annotated when it differs from this entity's canonical label.
subject surface form:
Superacids