Term | Definition |
Arrhenius's definition of an acid: | An acid is a substance that dissociates in water to produce a H+ ion. |
Limitations of Arrhenius's definition of an acid: | 1 . It's restricted to aqueous solutions .
2. X-ray crystallography shows a H+ ion does not exist independently (it combines with water to form a hydronium ion (H3O+)). |
Common acids: | Acetic acid - C2H4O2 - Found in vinegar.
Ascorbic acid - C6H8O6 - Vitamin C.
Benzoic acid- C7H6O2 - Adhesives.
Carbonic acid - H2CO3 - Fizzy drinks.
Citric acid - C6H8O7 - Citrus fruit. |
Dissociation | Is when molecules separate into smaller particles. |
Dissociation *note | A strong acid will completely dissociate in water.
A weak acid will slightly dissociate in water. |
Dissociation - Monobasic | A Monobasic acid is an acid that donates one proton (eg. a H+ ion). *Example: hydrochloric acid is a strong acid that dissociates as follows: HCl -> H+Cl- . |
Dissociation - Dibasic | A Dibasic acid is an acid that donates two protons (eg. 2H+ ions). *Example: Sulpheric acid is a strong acid that dissociates as follows: H2SO4 -> 2H+SO4*2- . |
Dissociation -Tribasic | A Tribasic acid is an acid that donates three protons ( eg. 3H+ ions ). *Example: Phosphoric acid is an weak acid that dissociates as follows: H3PO4 <=> 3H+PO4*3- . |
Amphoteric | (Eg. Water.)
It can act as both acid and base depending on its environment. |
Bronsted-Lowry definition of an acid: | An acid is a proton donor. |
Bronsted-Lowry's chemical properties of acids: | 1. Acid + base = salt + water.
2. Acid + metal = salt + hydrogen.
3. Acid + carbonate = salt + water + CO2. |
Arrhenius's definition of a base: | A base is a substance that dissociates with water to produce OH- ions. |
Limitations of Arrhenius's definition of a base: | NH3 (Ammonia) would not be considered a base under this definition. |
Examples of bases: | Sodium hydroxide - NaOH - clear drains.
Magnesium hydroxide - Mg(OH)2 - Gaviscon.
Calcium hydroxide - Ca(OH)2 - Limewater. |
Conjugate acid-base pair: | Is a pair consisting of an acid and a base that differ by one proton. |
Bronsted-Lowry definition of a base: | A base is a proton acceptor. |
Alkali | An alkali is a water soluble base. |
Neutralisation | Is a reaction between an acid and a base to form salt and water. |
Examples of neutralisation: | -Lime (CaO) - to neutralise soil.
-Sodiumhydrogencarbonate = gaviscon |