The chemical formula for citric acid is C₆H₈O₇. Citric acid is found in citrus fruits and is a naturally occurring weak organic acid. It is also an acidulant used in food and beverages. The structure consists of three carboxyl groups (-COOH) and one hydroxyl group (-OH), which comprises the acidity.

Physical Properties of Citric Acid

Appearance: White crystalline powder or colorless crystals.

Solubility

Water: Freely soluble in water, yielding a clear colorless solution. It is readily soluble at ordinary temperatures.

Solvents: Slightly soluble in ethanol and insoluble in ether.

Melting Point: About 153°C (307°F). Citric acid probably undergoes decomposition before melting at higher temperatures.

Density: About 1.665 g/cm³ for the solid.

Odor: Odorless.

Taste: It gives an acid taste, which is of course typical for this acid.

pH: Citric acid gives, in aqueous solution, an acid solution. The typical pH is about 2.2 to 2.8 at a solution strength of 1%.

Hygroscopic: Besides this, citric acid tends to absorb water from the air, a fact that could make it clump or partly dissolve if exposed to humid conditions.

Chemical properties of Citric Acid

Acidity: Citric acid contains three acidic protons. This means it is a triprotic acid. Thus, it can donate three protons in an aqueous solution.

Reaction with Bases: Citric acid reacts with a base to form citrate and water. For example, with sodium hydroxide

Reaction with Carbonates and Bicarbonates: When it reacts with a carbonate or bicarbonate, this forms carbon dioxide gas, water, and citrate salt.

Chelation: Citric acid forms chelates with metal ions because of more than one carboxyl and hydroxyl group. Example-with calcium ions

Application of Citric Acid

Food and Beverage:

Flavor Enhancer: A food additive employed in recipes to impart an acidic taste.

Preservative: It extends the life of food by lowering pH, which somehow restricts microbial development.

pH Modifier: Keeps the level of acidity in food at the appropriate level.

Cleaning Products:

Descaling Agent: Lime deposit or mineral accumulation in appliances and surfaces is removed.

Household Cleaner: Commonly employed when manufacturing cleaning agents because it acts efficiently in dissolving grease and grime.

Cosmetics and Personal Care:

pH Regulator: Utilized in cosmetic products to maintain stability.

Exfoliant: This chemical is added to skin care products as it has mild exfoliating properties.

Pharmaceuticals:

Antacid: Some antacid formulations have this chemical.

Drug Stabilizer: This chemical acts as a stabilizer for the pH and solubility of several drugs.

Industrial Applications

Chelating Agent: It is used in many industrial processes to perform the function of chelation of metallic ions.

Chemical Manufacturing: It is used either as a feedstock or a catalyst to manufacture other chemicals.

Agriculture

Soil Conditioner: It serves to condition the soil by enhancing its structural properties and making nutrients more available to plants.

Fertilizer Additive: It improves the effectiveness of fertilizers.

Conclusion

Citric acid is an organically versatile and popular organic acid with value in food and beverage, cleaning, cosmetics, pharmaceuticals, and industrial processes in agriculture for serving as a flavor enhancer, preservative, pH modifier, and chelator.

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