[Chemistry Class Notes] on Sodium Hexametaphosphate Pdf for Exam

Also known as Calgon, sodium hexametaphosphate is a chemical compound that consists of a mix of polymeric metaphosphates. It is a hexamer that contains repeated [(NaPO_{3})]units. This means that it is a polymer that has six molecular compositions of a monomer. This compound is soluble in water and has a circulation of multiple polyphosphate chain lengths. 

This compound forms as a result of a thermal procedure that is formed from monosodium orthophosphate. 

What is the Preparation of Sodium Hexametaphosphate? 

The compound [(NaPO_{3})_{6}], which is also popularly named Calgon, has a specific preparation procedure. The below steps explain it further. The complex can be obtained when monosodium orthophosphate goes through a thermal process or heating. Initially, it generates sodium acid pyrophosphate. The reaction is shown below as:

[ 2 NaH_{2}PO_{4} rightarrow  Na_{2}H_{2}P_{2}O_{7} + H_{2}O ]

Further, this pyrophosphate gets heated to generate the final complex (NaPO3)6 followed by rapid cooling. The chemical reaction gets depicted below as:

[ 3 Na_{2}H_{2}P_{2}O_{7} rightarrow  (NaPO_{3})_{6} + 3 H_{2}O ]

What are the Chemical Properties of this Compound?

• The boiling point of sodium hexametaphosphate is 1500 degrees Celsius. 

• It has a molecular weight of 611.7704 g mol-1.

• The atomic mass of Calgon is 30.

• It has a melting point of 62 degrees Celsius. 

• The monoisotopic mass of this compound is 611.689651 g/mol.

• For sodium hexametaphosphate, the topological polar surface area is calculated at 296 Ų.

• When exposed to water-based solutions, this compound can hydrolyse either into sodium trimetaphosphate or sodium orthophosphate. 

What are the Physical Attributes of this Compound?

• This has a slightly colourless or white appearance in the form of crystals and looks translucent or transparent under the light. 

• It has no characteristic odour. 

• It has a refractive index of 1.482 

• It is soluble in water but not in inorganic solvents. 

• It has a slightly higher ph value than water, at 8.6

Applications 

Sodium hexametaphosphate has various uses in industrial, consumer and agricultural purposes due to its intrinsic properties. Some of these include:

Industrial uses:

• To prepare solutions in industries for the production of ceramics, including additives is a mandatory step to obtain a proper fluid paste. Therefore, the compound [(NaPO_{3})_{6}] gets used as a dispersing agent in the manufacture of ceramics and enamels.

• It has been useful in the paint industry. 

• It is used to convert pulp into paper due to the nature of phosphates. 

• It is also used in the food preservation industry since it can keep food fresh for a longer time. 

• This also is used in toothpaste since it can reduce the formation of tartar in the mouth. 

• It is used in boilers in industries since it can reduce the hardness of water greatly. 

• It has wide applications in the ceramics industry. 

Agricultural and Consumer Uses:

• It also gets used in agricultural chemicals that help in the growth of plants and increase their productivity. It primarily gets applied for non-pesticidal purposes that do not interfere in pests’ interaction.

• It also gets used as a water-retaining agent. Due to this property, the complex finds its applications in meat and sausage processing. It enables non-vegetarian foods to last for a long period and reduces their anti-microbial activities.

• The compound also acts as a stabiliser for canned fruits, and milk, and it helps in maintaining its natural colour. Apart from these, it gets used in artificial maple syrup, packaged egg whites, fish fillets and salad dressing, etc.  It also gets used in beverages to store them for a longer span. 

Effects of Calgon 

Calgon or Graham’s Salt is a white powdery substance comprising sodium and metaphosphates. Although the chemical compound has wide-scale application in various sectors, yet these have some effects on human beings, and plants due to prolonged exposure.

The following pointers show some of its impacts. Read them to know more.

• Calgon can have a negative impact on the surroundings the environment if found in aquatic settings.

• It can induce vomiting and diarrhoea if it is inhaled or swallowed.

• The compound can also cause headache and dizziness when it gets absorbed by a person for short durations.

• It also causes fever, tiredness and low blood pressure when it gets injected in a body for a short span.

• The complex can also cause gastrointestinal infection and allergic reactions when someone comes in its exposure for fewer periods.

• Prolonged exposure to the compound can result in slower pulse rate, cyanosis and even coma along with acute spasms in the body and wrist.

• If anyone comes in close contact with the compound for a larger span, it causes pancreatic cancer. It is capable of increasing cancer-causing cells in the body.

• If someone comes in close contact with this compound, it can result in severe eye irritation. However, the severity of the circumstance varies with the prevalent concentration of this substance.

• Kidney problems are also an evident side-effect of the compound on a body.

• Direct
  contact of this chemical compound through open wounds, abrasions or lesions can result in damage to sensitive-skinned people.

• Loss of essential minerals from the bones can occur due to long-term exposure to the chemical