Main Difference – Lactate vs Lactic Acid
Lactic acid is commonly found in sour milk products such as yoghurt. Lactic acid causes the coagulation of casein protein present in fermented milk. The term lactate is used to name the anion formed from lactic acid. This anion is formed when lactic acid release one proton (hydrogen group). Lactic acid is a carboxylic acid. The proton is released from the carboxyl group to form the lactate ion. This is called the deprotonation of lactic acid. The main difference between lactate and lactic acid is that lactate ion is the dominant form in cellular fluids whereas lactic acid is less-dominant in cellular fluids.
Key Areas Covered
1. What is Lactate
– Definition, Chemical Properties
2. What is Lactic Acid
– Definition, Chemical Properties
3. What is the Difference Between Lactate and Lactic Acid
– Comparison of Key Differences
Key Terms: 2-Hydroxypropanoate, 2-Hydroxypropanoic acid, Anion, Carboxylic Acid, Deprotonation, Lactate, Lactic Acid, Milk, Proton
What is Lactate
Lactate is the anion formed from lactic acid when lactic acid undergoes deprotonation. The chemical formula of lactate is C3H5O3–. The molar mass of this ion is 89.07 g/mol. The IUPAC name of lactate ion is 2-Hydroxypropanoate. Lactate ion is an intermediate in the fermentation process of sugar.
Figure 1: Ball-Stick Model of Lactate Ion
When lactic acid is dissolved in water, it dissociates into lactate ion, releasing a proton. Lactate ion is the dominant form in solutions such as cellular fluid. Lactate ion has -1 electrical charge. The formation of lactate ion from lactic acid is mainly affected by the pH of the medium. The pka of lactic acid is about 3.86. But in cellular fluids, the pH is higher than this pka value. Therefore, lactic acid exists in the form of lactate ions.
Lactate is formed when we do exercises. During power exercises, the rate of demand for energy is high. Then, glucose is broken down to produce pyruvate, which is then converted into lactate. Then the lactate concentration is increased. This lactate is important in regenerating NAD+ which ensures that energy production is maintained.
What is Lactic Acid
Lactic acid is an organic compound and a carboxylic acid. The chemical formula of lactic acid is C3H6O3 and the molar mass of lactic acid is 90.078 g/mol. The IUPAC name of lactic acid is 2-Hydroxypropanoic acid.
Figure 2: Ball and Stick Model of Lactic Acid
Lactic acid is available as crystals or as a liquid. In its crystal form, the crystals are yellow to colorless and are odorless. In its liquid form, lactic acid is a syrupy liquid. The melting point of lactic acid is 16.8 °C, and the boiling point is 122 °C. Lactic acid is completely soluble in water. When dissolved in water, lactic acid undergoes deprotonation, forming lactate ion.
Lactic acid is a chiral molecule. It has two optical isomers: L-lactic acid and its mirror image D-lactic acid. These compounds exist in a racemic mixture. Lactic acid is a hygroscopic compound. This means it can absorb water when exposed to the atmosphere.
Difference Between Lactate and Lactic Acid
Definition
Lactate: Lactate is the anion formed from lactic acid when lactic acid undergoes deprotonation.
Lactic Acid: Lactic acid is an organic compound and is a carboxylic acid.
Chemical Formula
Lactate: The chemical formula of lactate is C3H5O3–.
Lactic Acid: The chemical formula of lactic acid is C3H6O3.
Molar Mass
Lactate: The molar mass of lactate ion is 89.07 g/mol.
Lactic Acid: The molar mass of lactic acid is 90.078 g/mol.
IUPAC Name
Lactate: The IUPAC name of lactate ion is 2-hydroxypropanoate.
Lactic Acid: The IUPAC name of lactic acid is 2-Hydroxypropanoic acid.
Electrical Charge
Lactate: Lactate has -1 electrical charge.
Lactic Acid: Lactic acid is neutrally charged.
Number of Hydrogen Atoms
Lactate: Lactate has 5 hydrogen atoms.
Lactic Acid: Lactic acid has 6 hydrogen atoms.
Stability
Lactate: Lactate is dominant in cellular fluids.
Lactic Acid: Lactic acid is less-dominant in cellular fluids.
Conclusion
Lactate ion is the conjugated base of lactic acid. Lactate ion is the dominant form of cellular fluids. That is because, at pH value of cellular fluids, lactic acid is ionized, forming lactate ion by releasing a proton. The main difference between lactate and lactic acid is that in cellular fluids, lactate ion is the dominant form whereas lactic acid is less-dominant.
Reference:
1. “Lactic acid.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
2. “Lactic acid.” Wikipedia, Wikimedia Foundation, 26 Dec. 2017, Available here.
3. “Lactate.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
Image Courtesy:
1. “Lactate-3D-balls” (Public Domain) via Commons Wikimedia
2. “Lactic-acid-3D-balls” (Public Domain) via Commons Wikimedia
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