Monday, May 6, 2013

How to determine if a compound is acidic?

Acidic compounds reduce pH when dissolved in solution. If an acidic compound is dissolved in freshly distilled water then it produces a solution with a pH below 7. According to definitions an acid is capable of producing hydrogen ions, or donating protons in solution, or accepts a lone pair of electrons in a reaction.

Some acids such as hydrochloric acid (HCl) completely dissociates when dissolved in water to produce hydrogen ions.  Other compounds might require a careful look at the chemical structure to give indication about its possible behaviour in solution. For example if a chemical compound contains carboxylic acid group (RCOOH) then this group is capable of donating a proton to generate a carboxylate ion. Other functional groups that render acidity include hydroxyl (ROH), sulfonic acids (RSO3H), and ammonium (RNH3+).

In addition, salts of basic compounds (conjugate acids) are acidic and reduce pH when dissolved in solution. For example, ephedrine is a basic compound. However, ephedrine hydrochloride is its salt which act as an acid in solution.

Some compounds might have the potential to act as an acid or as a base in solution. Such compounds are called ampholytes.




No comments:

Post a Comment

Thank you for your comment.