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Sodium Hexametaphosphate: Learn its Formula, Structure, Properties, Uses and Side Effects

Sodium hexametaphosphate is a water softener, commercially known as Calgon. The term Calgon is associated with calcium, which specifically indicates the elimination of calcium ions from water. The presence of calcium and certain cations in water enhances the water hardness, which in turn is reduced by applying powdered sodium hexametaphosphate, forming complexes with calcium and other ions. In 1963, the German chemists Erich Thilo and Ulrich Schülke discovered it by preparing sodium hexametaphosphate by heating anhydrous sodium trimetaphosphate.

Read on to learn more about its formula, structure, properties and uses in this Chemistry article.

Sodium Hexametaphosphate

Sodium Hexametaphosphate refers to a polymeric chemical compound. This phosphate is associated with six sodium metaphosphates and is represented by the chemical formula $N a_{6} (P O_{3})_{6}$ . The Hexametaphosphate atom contains six other atoms too. That is why it is called a hexamer. Sodium Hexametaphosphate compound is easily dissolved in water but not in organic solvents.

The primary material needed for its preparation is monosodium orthophosphate. This complex phosphate glass is synthesised in the lab by conducting thermal processes associated with soda ash and food-grade phosphoric acid. Moreover, as previously said, it has an expanding network of multiple polyphosphate chains.

Sodium Hexametaphosphate Structure

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From the above picture, it is revealed that the entire molecule has a cage-like appearance. If we look minutely, it is represented that six similar units of $N a P O_{3}$ are repeatedly attached to each other. That means the molecule is polymeric in nature. Sodium ions are linked with oxygen atoms. The phosphate group is stabilized by charge distribution and the opposite charge interactions between sodium and oxygens have well bounded the entire molecule.

Preparation of Sodium Hexametaphosphate

Initially, monosodium orthophosphate is heated to generate sodium acid pyrophosphate:

$2 N a H_{2} P O_{4} \to N a_{2} H_{2} P_{2} O_{7} + H_{2} O$

After that, the pyrophosphate is further heated to produce the sodium hexametaphosphate:

$3 N a_{2} H_{2} P_{2} O_{7} \overset{h e a t}{\to} (N a P O_{3})_{6} + 3 H_{2} O$

Just immediately, after the heating process is over, rapid cooling is followed.

Sodium Hexametaphosphate

Difference Between Sodium Hexametaphosphate and Sodium Polyphosphate

The difference between sodium hexametaphosphate and sodium polyphosphate is discussed below.

Parameters	Sodium Hexameta phosphate	Sodium Polyphosphate
Definition	Sodium Hexameta phosphate is an inorganic salt, represented by formula ( $N a_{6} (P O_{3})_{6}$ )	Sodium Polyphosphate is composed of sodium phosphate chains having formula $H_{2} N a_{2} O_{7} P_{2}$
Chemical category	Monomeric	Polymeric
Description	Specific six chain length form of sodium metaphosphate	An umbrella termed is used to name all the sodium phosphate units comprised of four or more units

Properties of Sodium Hexametaphosphate

The physical and chemical properties of sodium hexametaphosphate are given below:

Physical Properties
Chemical Formula	$N a_{6} (P O_{3})_{6}$
Density	2.48 g/cm³
Molecular weight/ Molar mass	611.77 g/mol
Boiling point	1,500 °C
Melting point	628 °C
Odour	Odourless
Appearance	White crystals
Refractive index	1.482
pH	8.6
Solubility	Soluble in water, insoluble in organic solvents.

Chemical Properties

When Sodium hexametaphosphate is dissolved in water, it hydrolyses, and under acidic conditions, sodium trimetaphosphate and sodium orthophosphate generates.

Sodium Hexametaphosphate is added to boiler water to inhibit the alkalinity.

Sodium Hexametaphosphate Uses

Sodium hexametaphosphate is used in different fields, such as industrial, consumer and agricultural purposes, etc. Let’s study its uses in detail.

Industrial Uses

Adding additives to solutions is a necessary step in ceramics manufacturing industries to achieve a fluid paste. To achieve a more uniform consistency, the compound is used as a dispersion agent during the production of ceramics and enamels.
It is also utilised in the paint industry.
Phosphates’ unique properties make them ideal for making paper from pulp.
As a result of its ability to extend the shelf life of perishable foods, it also finds use in the food preservation sector.
Since it prevents tartar from forming in the mouth, this is also included in certain toothpaste.
Industries use it in boilers because it considerably reduces the hardness of water.

Agricultural and Consumer Uses

It’s also a beneficial component of fertilizers and other agricultural compounds that nourish plant health and enhance yield. It is also applied as a substitute for pesticidal uses.
As having water retaining ability It prohibits the microbial decomposition of food products and promotes longevity of non veg foods .
The compound is also applied as a preservative agent for canned fruits, and milk, to sustain their original appearance.

Other Uses

Sodium hexametaphosphate is used for a variety of purposes such as industrial, consumer and agricultural purposes.

Sodium hexametaphosphate is used in solution processing as it can be applied as surfactant, emulsifier, suspending agent, dispersing agent and as a buffer.
This compound has a tendency to eliminate unwanted matter from solution by forming sticky clumps like coagulate , hence it is utilized in clay processing, drilling fluids and cleaning products which stick together forming clumps.
As capable of reducing hardness of water, it is affluently used in water treatment to prevent scale formation, corrosion, and biofilm formation in pipes and in other equipment by reducing metal ions via coagulation.

Sodium Hexametaphosphate Side Effects

Sodium hexametaphosphate is a whitish-powdery substance composed of sodium and metaphosphates. Although the chemical compound has numerous applications in various sectors, it also has negative impacts on plants and as well as on animals due to its prolonged exposure.

If found in aquatic settings, it can disbalance the aquatic ecology.
It can induce vomiting and diarrhoea on intake.
This compound can also induce headache and dizziness
If it is injected into body fluids, fever, tiredness and low blood pressure are observed
Gastrointestinal infection and allergic reactions can also be triggered by Sodium hexametaphosphate.
Prolonged exposure to the compound can reduce pulse rate, cyanosis, and even can cause coma disease along with acute spasms in the body and wrist. It is found as an oncogenic substance as it causes pancreatic cancer.
It promotes the growth of cancer-inducing cells in the body.
It is also the reason for eye irritation
Kidney problems can also arrive with side-effects of the sodium Hexametaphosphate compound on a body.
If sensitive-skinned people come into direct contact with this chemical compound through open wounds, it can result in skin damage.

Sodium hexametaphosphate (SHMP)

Sodium Hexametaphosphate: Learn its Formula, Structure, Properties, Uses and Side Effects

Sodium Hexametaphosphate: Learn its Formula, Structure, Properties, Uses and Side Effects

Sodium Hexametaphosphate

Sodium Hexametaphosphate Structure

Preparation of Sodium Hexametaphosphate

Sodium Hexametaphosphate

Difference Between Sodium Hexametaphosphate and Sodium Polyphosphate

Properties of Sodium Hexametaphosphate

Sodium Hexametaphosphate Uses

Sodium Hexametaphosphate Side Effects

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