Module 2: ACIDITY AND BASICITY OF ORGANIC COMPOUNDS Flashcards
- acids and bases are defined through three main concepts:
✓ Arrhenius Theory
✓ Brønsted-Lowry Theory
✓ Lewis electron pair Theory
BRønsted-Lowry Theory
- a “base” is any species that can _________________
- a Brønsted-Lowry base must have at least one lone pair of electron to be able to form bond with a proton
accept a proton
gives the exact strength of a given acid in water
Ka (acidity constant)
ArrHenius Theory
- “acid” is any species that can increase the concentration of ______________ in an aqueous solution
hydrogen ions (protons)
HCl → H+ + Cl–
ArrHenius Theory
- “base” is any species that can increase the concentration of _____________ in an aqueous solution
hydroxide ions, OH–,
NaOH → Na+ + OH–
BRønsted-Lowry Theory
- an “acid” is any species that can _________________________
- a Brønsted-Lowry acid must have a hydrogen that can dissociate as H+
donate a proton (H+)
___________ react almost completely with water
stronger acids (eg. inorganic acids)
Lewis “electron” pair Theory
- an “acid” is a species that can _______________
accept a pair of non-bonding electrons
in a Brønsted-Lowry acid-base reaction
a _______________ is the species formed after an acid donates its proton
conjugate base
HCl (aq) + H2O (l) → H3O+(aq) + Cl–(aq)
__________ acts as the Brønsted-Lowry acid; __________ is the conjugate base of HCl
- HCl
- Cl
react only slightly with water
weak acids (eg. acetic acid)
HCl (aq) + H2O (l) → H3O+(aq) + Cl–(aq)
__________ is the Brønsted-Lowry base; ________
is the conjugate acid of the water
- H2O
- H3O+
in a Brønsted-Lowry acid-base reaction
____________ is a species formed after the base accepts a proton
conjugate acid
acid strengths are normally given using
pKa values (pKa = –log Ka)
- note that the negative logarithm in the definition of pKa indicates an _____________ between Ka and pKa
inverse relationship
Lewis electron pair Theory
- suggest that acids react with bases, ___________, with no change in the oxidation numbers of any atoms
sharing a pair of electrons
Lewis electron pair Theory
- a “base” is a species that can ________________
donate a pair of non-bonding electrons
pOH
power of hydroxide
- the Lewis structure of “water” shows that it has a _________________________, therefore acting as the Lewis base
non-bonding pairs of valence electrons
- the reaction between a Lewis acid and a Lewis base gives rise to an _______________
acid-base complex or complex ion
- the “aluminum ion” (Al3+) suggests that it has free orbitals that can ________________________ donated by the water molecules, thereby acting as the Lewis acid
accept pairs of non-bonding electrons
pH means
power of hydrogen
- the acidity and basicity of a substance can be measured in terms of the molar ___________________________ ions, respectively
concentration of the hydrogen (H+) or hydroxide (OH–)
- pOH is defined as the _________________ ion concentration of a substance
negative logarithm of the OH–
- pH is defined as the _________________ ion concentration of a substance
negative logarithm of the H+
pH of battery acid
0 pH