The chemical formula for citrate is C6H5O7-3. This anionic form is a critical molecule in biological systems and various industrial applications.
Understanding Citrate: The Basics
Citrate is the conjugate base of citric acid, a weak organic acid widely recognized for its presence in citrus fruits like lemons and oranges. It plays an indispensable role in metabolism and serves as a versatile compound in many commercial products.
The question specifically asks for the formula of "citrate," which refers to the ion, not the neutral acid. At physiological pH levels, citric acid readily deprotonates (loses hydrogen ions) to form the polyvalent citrate ion.
The Chemical Formula of Citrate
The precise chemical formula for the citrate ion is C6H5O7-3. This formula provides a clear representation of its atomic composition and electrical charge.
Composition and Structure
Each citrate ion is characterized by:
- Six (6) Carbon atoms (C): These form the backbone of the molecule.
- Five (5) Hydrogen atoms (H): Attached to the carbon atoms.
- Seven (7) Oxygen atoms (O): These are primarily part of the carboxylate groups and one hydroxyl group.
- A net charge of -3: This negative charge arises from the deprotonation of its three carboxylic acid groups, making it a trivalent anion.
The composition can be summarized in the following table:
| Element | Number of Atoms |
|---|---|
| Carbon (C) | 6 |
| Hydrogen (H) | 5 |
| Oxygen (O) | 7 |
| Net Charge | -3 |
This specific arrangement allows citrate to function effectively in its various biological and chemical roles.
Role and Significance of Citrate
Citrate's distinct chemical structure gives it several crucial functions:
- Central Metabolic Intermediate: It is the first intermediate formed in the citric acid cycle (also known as the Krebs cycle), a metabolic pathway vital for aerobic respiration in nearly all organisms. In this cycle, acetyl-CoA combines with oxaloacetate to form citrate, initiating a series of reactions that generate energy.
- Chelating Agent: Citrate is an excellent chelator, meaning it can bind tightly to metal ions, especially calcium. This property is exploited in several applications.
- pH Buffer: Due to its multiple carboxylic acid groups, citrate acts as an effective buffering agent, helping to maintain stable pH levels in solutions.
Practical Applications
The unique properties of the citrate ion and its salts lead to a wide range of practical applications:
- Food and Beverage Industry:
- Used as a flavor enhancer in soft drinks, candies, and jams due to its tart taste.
- Acts as a preservative to prevent spoilage and maintain freshness.
- Functions as an acidifier and pH regulator.
- Medical and Pharmaceutical Use:
- Anticoagulant: Sodium citrate is commonly used in blood bags and during blood transfusions to prevent clotting by chelating calcium ions, which are essential for coagulation.
- Component in antacids to help neutralize stomach acid.
- Used in certain medications to improve absorption or palatability.
- Industrial Applications:
- Included in detergents and cleaning agents to soften water by sequestering metal ions that can interfere with cleaning.
- Used in cosmetics as a pH adjuster and chelating agent.
In summary, the formula C6H5O7-3 represents the citrate ion, a fundamental molecule with widespread importance in biochemistry, food science, and medicine.
