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Potassium Hydrogen Phosphate Formula – Structure, Properties, Uses, Sample Questions

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  • Last Updated : 13 May, 2022
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Potassium Hydrogen Phosphate consists of potassium, Hydrogen, Phosphorous, and Oxygen elements. Potassium is a silvery-white soft metal present in group-1 of the periodic table. Its atomic number is 19 and is represented by the symbol K. Hydrogen is the lightest, colorless, tasteless, and flammable gas. Its atomic number is one and is represented by the symbol H. Phosphorus is a highly reactive nonmetal present in group-15 of the periodic table. Its atomic number is 15 and is represented by the symbol P. Oxygen is a highly reactive nonmetal present in the chalcogen group, i.e., group-16. Its atomic number is eight and is represented by the symbol O. 

Potassium Hydrogen Phosphate Formula

Potassium Hydrogen Phosphate is an inorganic white odorless crystalline solid which is highly soluble in water. Its chemical formula is K2HPO4 and belongs to the group of potassium phosphates. It is the dipotassium salt of phosphoric acid (H3PO4). The other names for Potassium Hydrogen Phosphate are Dipotassium Phosphate, and Potassium Phosphate Dibasic. It is insoluble in ethanol.

Preparation of Potassium Hydrogen Phosphate

It is prepared by partial neutralizing phosphoric acid (H3PO4) with potassium hydroxide (KOH). The chemical reaction to prepare the Potassium Hydrogen Phosphate is given below-

H3PO4 + 2KOH → K2HPO4 + 2H2O

Structure of Potassium Hydrogen Phosphate

Potassium Hydrogen Phosphate consists of two potassium cations (K+) and one phosphate anion (HPO4-2) in which the phosphorous atom is attached to one hydroxyl group (OH), one double-bonded oxygen atom, and two single-bonded oxygen atoms.

Potassium Hydrogen Phosphate structure

Physical properties of Potassium Hydrogen Phosphate

  • The chemical formula of Potassium Hydrogen Phosphate is K2HPO4.
  • It appears in a white crystalline solid form.
  • It has no odor.
  • The melting point of Potassium Hydrogen Phosphate is greater than 465°C.
  • Its molecular weight is 174.2 g/mol.
  • The density of Potassium Hydrogen Phosphate is 2.44 g/cm3.
  • It is soluble in water.

Chemical properties of Potassium Hydrogen Phosphate

  • Potassium Hydrogen Phosphate reacts with hydrogen chloride to form phosphoric acid and potassium chloride.

K2HPO4 + 2HCl → H3PO4 + 2KCl

  • Potassium Hydrogen Phosphate reacts with sodium hydroxide base to form disodium hydrogen phosphate, Tripotassium phosphate, and water.

3K2HPO4 + 2NaOH → Na2HPO4 + 2K3PO4 + 2H2O

Uses of Potassium Hydrogen Phosphate

  • Potassium Hydrogen Phosphate is highly water-soluble so it is used in fertilizers because it delivers a high amount of phosphorous to the growing plants.
  • It is used to increase the pH value of milk which increases the micellar net charge.
  • It is also used as a food additive.
  • Potassium Hydrogen Phosphate is used as competitive displacement of calcium by sodium in the micelles.

Sample Questions

Question 1: Which food items contain Potassium Hydrogen Phosphate?

Answer:

Potassium Hydrogen Phosphate is used in macaroni and pasta. It is also used in animal products, meat, canned sauces, milk evaporated and in some chocolates. It is used as an emulsifier in some types of cheese.

Question 2: What is the role of Potassium Hydrogen Phosphate is a Preservative?

Answer:

Potassium Hydrogen Phosphate is highly effective in preventing coagulation when used as a food preservative and is generally used as a buffering agent on the non-dairy creamer market.

Question 3: Find the molar mass of compound K2HPO4.

Answer:

  • Atomic weight of each potassium = 39.0983
  • Atomic weight of each Hydrogen = 1.00784
  • Atomic weight of Phosphorus = 30.973762
  • Atomic weight of each Oxygen = 15.999

Molecular weight of K2HPO4 = (2 × 39.0983) + 1.00784 + 30.973762 + (4 × 15.999)

= 174.2

Question 4: What are the health effects of using Potassium Hydrogen Phosphate?

Answer:

Potassium Hydrogen Phosphate is not toxic and is considered as a safe food additive. However, excessive consumption of potassium salts can cause imbalance in the electrolyte levels, resulting in several symptoms such as vomiting, diarrhea, abdominal discomfort, nausea and limited absorption of necessary nutrients.

Question 5: How Phosphorous help our body?

Answer:

Phosphorus is responsible for enhancing the preservation, repair and restoration of healthy bones and teeth in our body.

Question 6: Why K2HPO4 compound is used as fertilizer?

Answer:

K2HPO4 is highly soluble in water and it delivers a high amount of phosphorous for plants to grow. So for this reason it is used as fertilizer.

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