As we've seen, an Homologous Series is family of similar substances which share the same general formula and the same functional group (reactive part of the molecules), so they react in similar ways.

With Alkanes the first four members were called Methane, Ethane, Propane and Butane.

With Alcohols the first four members were called Methanol, Ethanol, Propanol and Butanol.

With Carboxylic Acids the first four members were called Methanoic Acid, Ethanoic Acid, Propanoic Acid and Butanoic Acid.

The functional group in a Carboxylic Acid comes at the end of the chain and is often written as COOH

In the picture above the R could represent a Hydrogen atom, or a chain of Carbons.

To name an acid we:

1. Count the number of Carbon atoms in the chain

2. Remember that 1 Carbon is Meth, 2 Carbons is Eth, 3 Carbons is Prop, 4 Carbons is But

3. Add -anoic acid on the end

In Year 9 we learned that acids are substances that ionise when they dissolve in water and produce Hydrogen ions (H⁺)

eg HCl --> H⁺ _(aq) + Cl^-_(aq)

Hydrochloric acid is a strong acid because it ionises 100% - every HCl molecule breaks up.

Carboxylic acids are weak because only a few of the molecules ionise, most molecules dissolve and stay un-ionised.