Chapter 16 – Summary
16.1 Acids and Bases
A summary of key properties and characteristics of acids and bases commonly encountered in everyday life was provided.
- Both acids and bases release ions in water solution.
- Since both are capable of producing ions when dissolved in water, they are electrolytes.
- Since they are electrolytes, they are both capable of conducting electricity.
- Both acids and bases undergo neutralization reaction
Strong acids and bases are 100% ionized in aqueous solution. Weak acids and bases are less than 100% ionized in aqueous solution. Salts of weak acids or bases can affect the acidity or basicity of their aqueous solutions. A compound that can donate a proton (a hydrogen ion) to another compound is called a Brønsted-Lowry acid. The compound that accepts the proton is called a Brønsted-Lowry base. The species remaining after a Brønsted-Lowry acid has lost a proton is the conjugate base of the acid. The species formed when a Brønsted-Lowry base gains a proton is the conjugate acid of the base. Thus, an acid-base reaction occurs when a proton is transferred from an acid to a base, with formation of the conjugate base of the reactant acid and formation of the conjugate acid of the reactant base. Amphiprotic species can act as both proton donors and proton acceptors. Water is the most important amphiprotic species. It can form both the hydronium ion, H3O+, and the hydroxide ion, OH− depending on what it is reacting with.
16.2 Ionization of Water
An acid-base reaction occurs when a proton is transferred from an acid to a base, with formation of the conjugate base of the reactant acid and formation of the conjugate acid of the reactant base. Amphiprotic species can act as both proton donors and proton acceptors. Water is the most important amphiprotic species. It can form both the hydronium ion, H3O+, and the hydroxide ion, OH− when it undergoes autoionization:
The ion product of water, Kw is the equilibrium constant for the autoionization reaction:
16.3 Reactions in Acids and Bases
Chemical reactions are classified according to similar patterns of behaviour. Acid-base reactions involve the transfer of hydrogen ions between reactants.
General acid-base reactions, also called neutralization reactions can be summarized with the following reaction equation:
ACID(aq) + BASE(aq) → H2O(l) + SALT(aq) or (s)
- The DRIVING FORCE for a general acid-base reaction is the formation of water.
Gas-forming acid-base reactions can be with carbonates or metals. One example of an acid mixing with a carbonate is summarized in the following reaction equation:
ACID(aq) + NaHCO3 or Na2CO3(aq) → H2O(l) + CO2(g) + SALT(aq) or (s)
- The DRIVING FORCE for a gas-forming acid-base reaction is the formation of gas.
Reactions of acids with metal oxides results in the formation of salt and water.
16.4 Introduction to pH and pOH
The concentration of hydronium ion in a solution of an acid in water is greater than 1.0 × 10−7M at 25 °C. The concentration of