What Is Sodium Citrate Its Formula Preparation Reactions and Uses
Sodium citrate refers to sodium salts of citric acid. Monosodium citrate, disodium citrate, and trisodium citrate are the three types of sodium salts of citric acid. The three types of salts get collectively known as E number E 331. However, sodium citrate mostly refers to the third type, that is, trisodium citrate. Sodium citrate is a compound obtained after the alkalizing activity, and it’s a sodium salt of citrate. Its chemical formula is Na3C6H5O7. It gets majorly used in medicine as well as the food industry. In this article, you can learn about sodium citrate uses and the definition, frequently asked questions, etc.
What is Sodium Citrate?
It is a sodium salt of citrate, and it has an alkalinizing activity. You can also call it trisodium citrate. It gets widely used as a food preservative, anticoagulant for stored blood, and alkalization of urine to get rid of kidney stones. Sodium citrate formula is Na3C6H5O7. And below, you can see its structure.
(Image will be added soon)
Properties of Sodium Citrate
Its molecular formula is Na3C6H5O7, and its molecular weight or molar mass is 258.068 g/mol.
Its appearance is white and comes in the form of crystalline powder, or granular crystals.
It’s soluble in water and becomes deliquescent upon contact with moist air. It’s insoluble in alcohol.
It has a sour taste like citric acid.
It has a total number of seven hydrogen bond acceptors and one hydrogen bond donor.
Monoisotopic mass of sodium citrate is 257.973 g/mol.
The melting point of sodium citrate is anywhere > (greater than) 3000 Celsius or 572 oF; 573K.
Applications of Sodium Citrate
Sodium citrate has major applications in food and beverage, healthcare, and other industrial ones too. Below you can read them in detail.
Food and Beverage:
Sodium citrate gets used as an emulsifying salt in processed cheese products. It facilitates the melting of cheese without becoming greasy. It works as a buffering agent in combination with citric acid, and it offers accurate pH control necessary for numerous foods and beverages. Its main job is being a food additive, either for flavor to improve taste or preservation purposes.
Healthcare:
Sodium citrate works perfectly as an anticoagulant for the blood. Thus, it gets widely used for blood collection and storage purposes. It can provide relief from the discomfort in urinary tract infections. It is also a great laxative and reduces several acidosis issues. It’s a significant ingredient of WHO’s oral rehydration solution. It also serves as an antacid, especially before anaesthesia.
You can easily find sodium citrate in many pharmaceutical products, colour, cosmetics, and deodorants. It’s also present in hair care, oral care, skincare, and bathing products.
Industrial Applications:
Citric acid gets used as an industrial cleaner. It helps with clearing steam blocks, hot water systems of calcium and rust layers. It also serves as a buffering and complexing agent in electroplating processes. Textile and building industry gets benefited by the chelating ability and non-toxicity of citric acid.
FAQs on Sodium Citrate Structure Properties and Applications in Chemistry
1. What is sodium citrate?
Sodium citrate is the sodium salt of citric acid with the chemical formula Na3C6H5O7. It is commonly known as trisodium citrate and forms when citric acid reacts with sodium hydroxide. In chemistry and industry, sodium citrate is used as a buffering agent, food additive (E331), and anticoagulant. It appears as a white crystalline solid and is highly soluble in water.
2. What is the chemical formula of sodium citrate?
The chemical formula of sodium citrate is Na3C6H5O7. It consists of three sodium ions (Na+) combined with one citrate ion (C6H5O73-). The citrate ion is derived from citric acid (C6H8O7) after losing three acidic hydrogen ions (H+).
3. How is sodium citrate prepared?
Sodium citrate is prepared by neutralizing citric acid with sodium hydroxide in a simple acid–base reaction. The balanced chemical equation is:
C6H8O7(aq) + 3NaOH(aq) → Na3C6H5O7(aq) + 3H2O(l)
Steps involved:
- Citric acid is dissolved in water.
- Sodium hydroxide solution is added slowly.
- The solution is evaporated to obtain solid sodium citrate crystals.
4. Is sodium citrate an acid, base, or salt?
Sodium citrate is a salt formed from a weak acid (citric acid) and a strong base (sodium hydroxide). Because it comes from a weak acid and strong base, its aqueous solution is slightly basic (alkaline). In water, citrate ions can react with water to produce a mildly basic solution, making sodium citrate useful as a buffering agent.
5. Why is sodium citrate used as a buffer?
Sodium citrate is used as a buffer because it helps maintain a stable pH by resisting changes in acidity or alkalinity. It works together with citric acid to form a citrate buffer system. The buffering action occurs due to the equilibrium:
C6H5O73-(aq) + H+(aq) ⇌ C6H6O72-(aq)
This equilibrium allows the solution to neutralize added acids or bases, making sodium citrate important in biochemical and laboratory applications.
6. What is the molar mass of sodium citrate?
The molar mass of sodium citrate (Na3C6H5O7) is approximately 258.07 g/mol. The calculation is:
- Na: 22.99 × 3 = 68.97 g/mol
- C: 12.01 × 6 = 72.06 g/mol
- H: 1.008 × 5 = 5.04 g/mol
- O: 16.00 × 7 = 112.00 g/mol
7. How does sodium citrate act as an anticoagulant?
Sodium citrate acts as an anticoagulant by binding calcium ions (Ca2+) in blood. Calcium ions are essential for blood clotting reactions. Sodium citrate forms soluble complexes with Ca2+, reducing free calcium concentration and preventing coagulation. Because this process is reversible, sodium citrate is widely used in blood collection tubes for laboratory testing.
8. What happens when sodium citrate is dissolved in water?
When sodium citrate dissolves in water, it dissociates into sodium ions and citrate ions. The dissociation equation is:
Na3C6H5O7(s) → 3Na+(aq) + C6H5O73-(aq)
The citrate ion can react slightly with water, making the solution mildly basic. This property explains its role in pH control and buffer solutions.
9. What is the difference between citric acid and sodium citrate?
The main difference is that citric acid is an acid, while sodium citrate is its sodium salt. Key differences include:
- Citric acid: Formula C6H8O7, weak organic acid, releases H+ in water.
- Sodium citrate: Formula Na3C6H5O7, salt formed after neutralization.
- Citric acid lowers pH, while sodium citrate helps buffer and slightly raises pH.
10. What are the common uses of sodium citrate in chemistry and industry?
Sodium citrate is commonly used as a buffering agent, food additive, and anticoagulant in chemistry and industry. Major uses include:
- Buffer solutions in laboratories and biochemistry.
- Food additive (E331) for flavor control and preservation.
- Anticoagulant in blood collection tubes.
- Water softening agent by binding Ca2+ and Mg2+.
