Module 2

Lesson 1.9  Introducing the Carboxylic Acids



Key Concepts


Carboxylic acids are a family of organic compounds characterized by a carboxyl functional group (-COOH). As illustrated below, the carboxyl functional group is composed of a carbonyl functional group (C=O) attached to a hydroxyl functional group (-OH). The carboxyl group is always at the end of a carbon chain or branch. The general formula for a carboxylic acid is R-COOH. R represents a hydrocarbon or a hydrogen atom.



Fig. 1  general formula for a carboxylic acid


 
 

Some carboxylic acids contain two, three, or more carboxyl groups.


Fig. 2  oxalic acid


Fig. 3  tartaric acid


Fig. 4  citric acid


Carboxylic acids have a sour, tangy taste and a distinctive odour. They occur naturally in citrus fruits, crab apples, rhubarb, and other foods. Many common products contain carboxylic acids. Some common examples include the following:






 
 
Fig. 5  methanoic acid (formic acid)
 
 







 
 
Fig. 6  Ethanoic acid (acetic acid or vinegar)
 
 





 
 
Fig. 7  oxalic acid
 
 

 Read pages 436 to 437 in the textbook to learn more about carboxylic acids.