Acids and Bases Definitions Quiz

Study Notes

Arrhenius Definition of Acids and Bases

Arrhenius acids release hydrogen ions (H+) or hydronium ions (H3O+) in solution.
H+ ions in water are associated with water molecules to form hydronium ions (H3O+).
Examples of Arrhenius acids: HF (hydrofluoric acid), HCl (hydrochloric acid), H2SO4 (sulfuric acid), HNO3 (nitric acid).
Arrhenius bases release hydroxide ions (OH-) in solution.
Arrhenius acid donate H+ ions to water creating hydronium ions (H3O+) and their conjugate base.
Arrhenius bases dissociate in water to produce metal ions and hydroxide ions (OH-).
Examples of Arrhenius bases: NaOH (sodium hydroxide), KOH (potassium hydroxide), Ca(OH)2 (calcium hydroxide).

Brønsted-Lowry Definition of Acids and Bases

Brønsted-Lowry acids are proton (H+) donors.
Brønsted-Lowry bases are proton (H+) acceptors.
When an acid donates a proton, it forms its conjugate base.
When a base accepts a proton, it forms its conjugate acid.
- To find the conjugate acid: Add one hydrogen and increase the charge by one.
- To find the conjugate base: Remove one hydrogen and decrease the charge by one.
Examples of Brønsted-Lowry acid-base reactions:
- HF (hydrofluoric acid) + H2O (water) → H3O+ (hydronium ion) + F- (fluoride ion)
  - HF is the Brønsted-Lowry acid (proton donor)
  - H2O is the Brønsted-Lowry base (proton acceptor)
  - H3O+ is the conjugate acid of H2O
  - F- is the conjugate base of HF
- CO32- (carbonate ion) + H2O (water) → HCO3- (bicarbonate ion) + OH- (hydroxide ion)
  - H2O is the Brønsted-Lowry acid (proton donor)
  - CO32- is the Brønsted-Lowry base (proton acceptor)
  - HCO3- is the conjugate acid of CO32-
  - OH- is the conjugate base of H2O

Lewis Definition of Acids and Bases

Lewis acids are electron pair acceptors.
Lewis bases are electron pair donors.
Lewis acids often have an incomplete octet and can accept electron pairs.
Lewis bases have lone pairs of electrons they can donate.
Lewis base is also known as a nucleophile (electron-rich).
Lewis acid is also known as an electrophile (electron-poor).
Example of a Lewis acid-base reaction:
- BH3 (borane) + NH3 (ammonia) → BH3-NH3 (ammonia-borane adduct)
  - BH3 is the Lewis acid (electron pair acceptor)
  - NH3 is the Lewis base (electron pair donor)
  - The nitrogen atom in NH3 donates a lone pair of electrons to the empty orbital on boron in BH3.

Key Concepts

Conjugate acid: the species formed when a base accepts a proton.
Conjugate base: the species formed when an acid donates a proton.
Nucleophile: an electron-rich species attracted to electron-poor centers, typically a Lewis base.
Electrophile: an electron-poor species attracted to electron-rich centers, typically a Lewis acid.

Description

Test your knowledge on the definitions of acids and bases according to Arrhenius, Brønsted-Lowry, and Lewis theories. This quiz covers key concepts including ion release, proton donation, and electron pair acceptance. Understand the differences and examples of each type.