Properties, Preparation and Uses of Sodium Pyrophosphate

What is Sodium Pyrophosphate?

Sodium pyrophosphate also referred to as tetrasodium pyrophosulphate, tetrasodium phosphate or TSPP is an inorganic compound having the formula Na₄P₂O7. It Isa white water soluble solid that is composed of pyrophosphate anions and sodium ions.

Pyrophosphate Anions

Pyrophosphate anions are phosphorus oxyanions that contain two phosphorus atoms in a P-O-P linkage.

Sodium Ions (Na+)

Sodium ions refers to the principal extracellular cation and solute that is essential for the generation of action potentials in the body. It is a soft, silver-white chemically active metallic element that occurs naturally only in combination.

Properties of Sodium Pyrophosphate

The following are some of the physical and chemical properties of sodium pyrophosphate.

IUPAC NAME 

The IUPAC name for sodium pyrophosphate is Tetrasodium diphosphate.

OTHER NAMES

Other names that can be used when identifying sodium pyrophosphate are:

  • Pyrophosphate
  • Sodium pyrophosphate
  • Tetrasodium pyrophosphate (anhydrous)
  • TSPP

CHEMICAL FORMULA 

The chemical formula of sodium pyrophosphate is Na₄P₂O7.

MOLAR MASS 

Sodium pyrophosphate has a molar mass of 265.9 g/mol.

APPEARANCE 

Sodium pyrophosphate has a colorless appearance but it can also be seen as white crystals.

ODOR 

Sodium pyrophosphate is odorless.

DENSITY 

Sodium pyrophosphate has a density of 2.534 g/cm3.

MELTING POINT 

Sodium pyrophosphate has a melting point of 988 °C (1,810 °F; 1,261 K) (anhydrous)

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79.5 °C (decahydrate).

BOILING POINT 

Sodium pyrophosphate decomposes at this point.

SOLUBILITY IN WATER 

The solubility of sodium pyrophosphate in water is 2.61 g/100 mL (0 °C)

6.7 g/100 mL (25 °C)

42.2 g/100 mL (100 °C).

SOLUBILITY

Sodium pyrophosphate is insoluble in alcohol but soluble in water.

REFRACTIVE INDEX 

The refractive index of sodium pyrophosphate is 1.425.

STRUCTURE 

Sodium pyrophosphate has a monoclinic crystal structure (decahydrate).

HEAT CAPACITY 

Sodium pyrophosphate has a heat capacity of 241 J/mol K.

STD MOLAR ENTROPY 

The Std Molar Entropy for sodium pyrophosphate is 270 J/mol K.

STD ENTHALPY OF FORMATION 

The Std Enthalpy of Formation for sodium pyrophosphate is -3166 kJ/mol.

GIBBS FREE  ENERGY 

Sodium pyrophosphate has -3001 kJ/mol amount of Gibbs Free Energy.

Preparation/Production of Sodium Pyrophosphate 

Tetrasodium pyrophosphate also referred to as sodium pyrophosphate is produced by the reaction of sodium carbonate with furnace-grade phosphoric acid to form disodium phosphate, which is further heated to form tetrasodium pyrophosphate.

Chemical Structure of Sodium Pyrophosphate

The chemical structure of sodium pyrophosphate is Na₄P₂O7, which simply implies that there are four atoms of sodium, two atoms of phosphorus and seven atoms of oxygen present in this compound.

Uses of Sodium Pyrophosphate

Sodium pyrophosphate is used as;

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1. Buffering Agents

2. Emulsifiers

3. Dispersing Agents

4. Thickening Agents

5. Food Additives – Examples of food containing sodium pyrophosphate are; chicken nuggets, marshmallows, pudding, crabmeat, canned tuna, soya-based meat alternatives, cat food and treats.

6. Toothpaste – In toothpaste sodium pyrophosphate acts as a tartar control agent which helps in the removal of calcium and magnesium from saliva, this preventing them from being deposited on the teeth.

7. Dental Rinses – It is used in commercial dental rinses before brushing to aid plaque reduction.

8. Detergents – It is used as detergents to prevent similar deposition on clothing, but due to the phosphate content present, it causes eutrophication of water therefore promoting algae growth.

Eutrophication 

Eutrophication is defined as the process by which an entire body of water, or parts of the water becomes enriched with minerals and nutrients like nitrogen and phosphorus leading to an increase in the production of algae and macrophytes.

Hazardous Effects of Sodium Pyrophosphate

Despite the number of good uses of sodium pyrophosphate, there are also some bad effects to this chemical, they include;

  1. Sodium pyrophosphate causes skin irritation such as rashes, hives, itching, red swollen blisters, peeling of the sikin, wheezing etc.
  2. Sodium pyrophosphate can cause damage to the kidneys.
  3. Sodium pyrophosphate can cause serious eye irritation and is very harmful when swallowed.
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Precautions to Carryout While Handling Sodium Pyrophosphate

When working with or using sodium pyrophosphate, the following should be ensured in other to avoid certain health complications and damages.

  1. Ensure there is adequate ventilation when working with sodium pyrophosphate.
  2. Make use of appropriate protective eyeglasses or chemical safety googles.
  3. Wear appropriate protective gloves and clothing to prevent skin exposure.

Compounds Related to Sodium Pyrophosphate

  • Other Anions

  • Trisodium phosphate
  • Pentasodium triphosphate
  • Sodium hexmetaphosphate
  • Other Cations

  • Tetrapotassium pyrophosphate
  • Related Compounds

  • Disodium pyrophosphate

Frequently Asked Questions Concerning Sodium Pyrophosphate

  • What are the side effects of using sodium pyrophosphate?

Sodium Pyrophosphate is an irritant , and taking it in can result to injury in the mouth, throat and gastrointestinal tract leading to nausea, vomiting, cramps and even diarrhea.

  • Is sodium pyrophosphate a toxic compound?

Yes. Sodium Pyrophosphate is considered toxic and hazardous.

  • How is Sodium Pyrophosphate stored?

Sodium Pyrophosphate is stored by keeping it in a tightly closed container and keeping it in a cool, dry, ventilated area to prevent it against physical damage.

  • Is Sodium Pyrophosphate soluble?

Sodium Pyrophosphate is soluble in water and insoluble in alcohol.