Sodium Citrate Formula – Structure, Properties, Uses, Sample Questions

Sodium is an alkali metal and the 6th most copious element present in the earth’s crust. It comes under group 1 of the periodic table and is represented by the symbol Na (Derived from the word Natrium). Sodium is white, soft, silvery, and highly reactive in nature. Oxygen is a member of the chalcogen family and 3rd most copious element present in-universe the after Hydrogen and Helium. It comes under group 16 of the periodic table and is represented by the symbol O. It is highly reactive in nature and is a nonmetal. It is an oxidizing agent and forms oxides with different elements and compounds. At STP it exists in the diatomic form O₂. Hydrogen is the first and most copious element present in the atmosphere. It comes under group 1 of the periodic table and is represented by the symbol H. It is colorless, odorless, tasteless, highly combustible in nature, and the lightest element. At STP it exists in diatomic form H₂. 

Sodium Citrate Formula

Sodium citrate is the trisodium salt of citric acid. Its component compounds are sodium and citric acid. Its molecular formula is represented as C₆H₅Na₃O₇ or C₆H₅O₇. 3Na or Na₃C₆H₅O₇  and its molecular weight is 258.06 g/mol. The IUPAC names of sodium citrate are Trisodium citrate or Trisodium 2-hydroxypropane-1,2,3-tricarboxylate. It is also called synonyms like Natrocitral Citrosodine.

Citric acid upon reaction with sodium bicarbonate in presence of water in bath bomb results in the formation of  Sodium citrate.

C₆H₈O₇  + 3NaHCO₃ + H₂O ⇢ Na₃C₆H₅O₇ + 3H₂O + 3CO₂

Properties of Sodium Citrate

• Physical appearance: It is a white crystalline or granular powder and mildly deliquescent when exposed to moist air. 
• Boiling point: It undergoes decomposition upon exposure to red heat.
• Melting point: According to the Material safety data sheet, its melting point is 300° C. But as per International Chemical Safety Cards (ICSC), its melting point is > 300° C.
• Solubility: It is stable in dry air; it becomes anhydrous when exposed to a temperature of 150 °C. It is 1.3 parts soluble in water, and 0.6 parts soluble in boiling water. It is practically not soluble in alcohol. Its solubility according to material safety data sheets is 29 gram/Litre and International Chemical Safety Cards (ICSC) is 42.5 gram/100ml at 25 C.
• pH: According to EU good improvement agents its pH is between 7.5 and 9.0.
• Density: its density is 1.7 g/cm³

Applications in medicine

• It has the ability to alter the pH of blood and urine by increasing the alkalinity. This nature of sodium citrate is useful to avoid kidney stones.
• It is also used in treating metabolic acidosis, a type of renal issue that occurs in some people.
• Sodium citrate acts as a buffer and serves as a neutralizing agent to treat excess acid in the stomach.

Na₃C₆H₅O₇ + 3HCl (aqueous) ⇢ C₆H₈O₇ + 3NaCl_(aq)

• It is also used as a constituent for preventing coagulation of whole blood during sampling of blood, hemodialysis, and haemofiltration. sodium citrate reacts with calcium and prevents blood clotting. It is precipitated as oxalate (crystals of which may be seen in oxalate blood) these are insoluble or bound in a non-ionized state.

Applications in industry 

• Sodium citrate is used as a flavor, and preservative to avoid microbial contamination (i.e as a food additive). It is used in cheese production as an oil emulsifier.
• In cosmetics, it is used as a buffering agent to maintain the pH level
• Sodium citrate is used in refreshing and soft drinks, and beverages to reduce sour taste and enhance the taste.
• It is used in dishwashing, laundry products, and in surface-active agents. 

Sample Questions

Question 1: What are the medical applications of Sodium citrate?

Answer:

• It has the ability to alter the pH of blood and urine by increasing the alkalinity. This nature of sodium citrate is useful to avoid kidney stones.
• It is also used in treating metabolic acidosis, a type of renal issue that occurs in some people.
• Sodium citrate acts as a buffer and serves as a neutralizing agent to treat excess acid in the stomach.
• It is also used as a constituent for preventing coagulation of whole blood during sampling of blood, hemodialysis and haemofiltration. 

Question 2: What are the industrial applications of sodium citrate?

Answer:

• Sodium citrate is used as a flavor, and preservative to avoid microbial contamination (i.e as a food additive). It is used in cheese production as an oil emulsifier.
• In cosmetics, it is used as a buffering agent to maintain the pH level.
• Sodium citrate is used in refreshing and soft drinks, and beverages to reduce sour taste and enhance the taste. 
• It is used in dishwashing, laundry products, and surface-active agents.
  

Question 3: What is the IUPAC name of commonly used Sodium citrate and what are the synonyms of Sodium citrate?

Answer:

The IUPAC names of sodium citrate are Trisodium citrate or Trisodium 2-hydroxypropane-1,2,3-tricarboxylate. It is also called synonyms like Natrocitral Citrosodine.

Question 4: Explain the solubility of Sodium citrate?

Answer: 

It is stable in dry air; it becomes anhydrous when exposed to a temperature of 150 °C. It is 1.3 parts soluble in water, and 0.6 parts soluble in boiling water. It is practically not soluble in alcohol.

Its solubility according to material safety data sheets is 29 grams/Litre and International Chemical Safety Cards (ICSC) is 42.5 grams/100ml at 25° C.

Question 5: Write about the formation of sodium citrate with the reaction?

Answer: 

Citric acid reacts with sodium bicarbonate in presence of water in a bath bomb and forms Sodium citrate.

C₆H₈O₇  + 3NaHCO₃ + H2O ⇢ Na₃C₆H₅O₇ + 3H₂O + 3CO₂

Question 6: How trisodium citrate acts as a neutralizing agent for writing reaction?

Answer: 

Sodium citrate acts as a buffer and serves as a neutralizing agent to treat excess acid in the stomach.

Na₃C₆H₅O₇ + 3HCl (aqueous) ⇢ C₆H₈O₇ + 3NaCl(aq)