Introduction Carbonyl (-C=O)and hydroxyl (-OH)on the same carbon is carboxyl group. Carboxyl group is usually written-COOH. Aliphatic acids have an alkyl group bonded to -COOH. Aromatic acids have an aryl group. Fatty acids are long-chain aliphatic acids. R-C-0-H+H,0:→ +H,O+ pK,=5 (K≡105) acid => 2 carboxylateChapter 20 2 Introduction • Carbonyl (-C=O) and hydroxyl (-OH) on the same carbon is carboxyl group. • Carboxyl group is usually written -COOH. • Aliphatic acids have an alkyl group bonded to -COOH. • Aromatic acids have an aryl group. • Fatty acids are long-chain aliphatic acids. =>