Benzoic acid conjugate base, also known as benzoate anion, is a negatively charged species that forms when benzoic acid, a weak organic acid, loses a proton. This conjugate base is characterized by its resonance-stabilized structure, which distributes the negative charge over multiple carbon atoms. The benzoate anion exhibits a strong affinity for metal ions, forming stable coordination complexes, and it plays a significant role in various biological and industrial processes.
Structure of Benzoate Ion, the Conjugate Base of Benzoic Acid
Benzoic acid is a weak organic acid that can donate a proton (H+) in water to form its conjugate base, the benzoate ion. The structure of the benzoate ion is delocalized over the benzene ring, resulting in a resonance hybrid with three equivalent resonance structures.
Resonance Structures of Benzoate Ion:
| Resonance Structure 1 | Resonance Structure 2 | Resonance Structure 3 |
|---|---|---|
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Key Features:
- The negative charge is evenly distributed over the three oxygen atoms in the ring.
- The C-O bond lengths are identical (126 pm), indicating resonance delocalization.
- The benzene ring is planar with a hexagonal shape.
Stability of Benzoate Ion:
The delocalization of the negative charge makes the benzoate ion highly stable. This stability contributes to the weak acidity of benzoic acid and its ability to form stable salts with strong bases.
Applications:
Benzoate ion is commonly used as a preservative in food and beverages due to its antimicrobial properties. It is also found in some pharmaceuticals and cosmetic products.
Question 1:
What is the benzoic acid conjugate base?
Answer:
The benzoic acid conjugate base is the anion formed when a hydrogen ion is removed from benzoic acid. It is a resonance-stabilized anion with the negative charge delocalized over the carboxylate group. The conjugate base is denoted as benzoate.
Question 2:
How is the benzoic acid conjugate base formed?
Answer:
The benzoic acid conjugate base is formed by the dissociation of benzoic acid in water. This reaction is an acid-base reaction, where benzoic acid acts as an acid and water acts as a base. The equilibrium constant for this reaction is denoted as Ka, and it is a measure of the strength of benzoic acid as an acid.
Question 3:
What are the properties of the benzoic acid conjugate base?
Answer:
The benzoic acid conjugate base is a weak base with a pKa of 4.2. It is soluble in water and has a relatively strong UV absorbance. The benzoate anion is a good chelating agent and can form complexes with metal ions. It is also used as a food preservative due to its antimicrobial properties.
And that’s all there is to benzoic acid and its conjugate base, folks! Hope you enjoyed this little chemistry lesson. If you have any more questions, don’t hesitate to ask. And be sure to check back later for more exciting chemistry adventures. Thanks for reading!