What is Dipotassium Phosphate Definition Formula Preparation and Uses in Chemistry
What Is Dipotassium Phosphate?
Dipotassium Phosphate is an inorganic compound which is an extremely water-soluble salt. It is generally used as a fertiliser as it is a great source of potassium and phosphorus. It is also used as a food additive as a good source for potassium and phosphorus. It also finds its application as a buffering agent. Buffering agents are used to maintain the pH value of a solution near a particular chosen value. It is added during a chemical process so as to reduce the rapid change in the composition of the compound when acids or bases are added to it. There are different types of acid and base buffers like acetic acid, sodium acetate, sodium bicarbonate etc.
Structure of Dipotassium Phosphate
The molecular formula or the dipotassium phosphate formula is: K2HPO4
The K2HPO4 name is also known as dipotassium hydrogen orthophosphate, potassium phosphate dibasic.
The picture below depicts the K2HPO4 structure: -
[Image will be Uploaded Soon]
Characteristics of Dipotassium Phosphate
The IUPAC name of this compound is dipotassium hydrogen phosphate
The density of Dipotassium Phosphate is 2.44g/cm3
The K2HPO4 molecular weight or molar mass is 174.2g/mol
It accepts four hydrogen bonds
The melting point of this compound is greater than 465 °C
The chemical formula of the compound is K2HPO4
It is freely soluble in water
It is insoluble in ethanol
The production of K2HPO4 is done in the process of condensation of phosphoric acid using potassium hydroxide
As a result, Phosphoric acid is manufactured from the rock of phosphate, which is found commonly in several places around the globe.
Physical Properties of Dipotassium Phosphate (K2HPO4)
The Dipotassium Phosphate compound is odourless
The colour of the compound is white
It is a deliquescent solid which means that it tends to absorb moisture from the air and dissolve in it
It is a three covalently bonded unit
The molecule of this compound has a heavy atom count of 7
The complexity of the compound is 4605
The compound can be easily soluble in water
Chemical Properties of Dipotassium Phosphate (K2HPO4)
Reaction with hydrochloric acid (HCL)
The compound Dipotassium Phosphate when reacts with hydrochloric acid, it forms potassium chloride and phosphoric acid. The chemical equation of the reaction is given below: -
K2HPO4 + 2HCl → 2KCl + H3PO4
Reaction with sodium hydroxide (NaOH)
The compound dipotassium hydrogen phosphate when reacts with a base, sodium hydroxide it forms disodium hydrogen phosphate and water.
2NaOH + 3K2HPO4 → 2K3PO4 + 2H2O + Na2HPO4
Uses of Dipotassium Phosphate
Dipotassium phosphate is used in fertilisers. It is used as a component of fertilisers because of its highly water-soluble nature. It supplies the growing plants with a large percentage of phosphorus.
It is used as a food additive. The grades of dipotassium hydrogen phosphate used in foods are different than that which are used in fertilisers.
It is added in milk to increase its pH. This is done in order to increase the net micelle charge. Micelles are aggregates of molecules.
It is used in the micelles as a competitive displacement of calcium by sodium.
Example Questions
Q1) Why is the Role of Phosphorus in Our Body?
Phosphorus is quite responsible for enhancing the preservation, repair and restoration of healthy bones and teeth in your body. Phosphate is essential in their normal function in the context of muscular performance, and how effectively they contract.
Q2) Which Foods Contain Disodium Phosphate?
Disodium phosphate is often used in food products, macaroni and pasta included. It is also used as an emulsifier in some cheeses. It can also be used in animal products, meat, canned sauces, Jell-O, milk evaporated and some chocolate.
Q3) What is the Role of Disodium Phosphate When it is Used as a Preservative?
Dipotassium Phosphate (DKP) is an effective buffering agent for a range of balancing agent-functioning uses. Dipotassium Phosphate is highly effective in preventing coagulation when used as a food additive or preservative and is generally used as a buffering agent on the non-dairy creamer market.
FAQs on Dipotassium Phosphate K2HPO4 Structure Properties and Applications
1. What is dipotassium phosphate?
Dipotassium phosphate is an inorganic salt with the chemical formula K2HPO4, formed from potassium ions and the hydrogen phosphate ion.
It consists of:
- Two K+ ions
- One HPO42- ion
It is commonly used as a buffer solution component, fertilizer, and food additive. Dipotassium phosphate is also known as potassium hydrogen phosphate in IUPAC nomenclature.
2. What is the chemical formula of dipotassium phosphate?
The chemical formula of dipotassium phosphate is K2HPO4.
The formula shows:
- 2 potassium atoms (K)
- 1 hydrogen atom (H)
- 1 phosphorus atom (P)
- 4 oxygen atoms (O)
It is derived from partial neutralization of phosphoric acid (H3PO4), where two acidic protons are replaced by potassium ions.
3. How is dipotassium phosphate prepared?
Dipotassium phosphate is prepared by the partial neutralization of phosphoric acid (H3PO4) with a potassium base.
A common preparation reaction is:
H3PO4(aq) + 2KOH(aq) → K2HPO4(aq) + 2H2O(l)
Steps:
- React phosphoric acid with potassium hydroxide.
- Control stoichiometry to replace only two acidic hydrogens.
- Evaporate the solution to crystallize solid K2HPO4.
4. Is dipotassium phosphate acidic, basic, or neutral?
Dipotassium phosphate is a weakly basic salt in aqueous solution.
It behaves as a base because the HPO42- ion can accept a proton:
HPO42-(aq) + H2O(l) ⇌ H2PO4-(aq) + OH-(aq)
Since it is formed from a strong base (KOH) and a weak acid (H3PO4), its aqueous solution has a pH greater than 7.
5. What is the molar mass of dipotassium phosphate?
The molar mass of dipotassium phosphate (K2HPO4) is approximately 174.18 g/mol.
Calculation:
- K: 39.10 × 2 = 78.20 g/mol
- H: 1.01 g/mol
- P: 30.97 g/mol
- O: 16.00 × 4 = 64.00 g/mol
Total = 78.20 + 1.01 + 30.97 + 64.00 ≈ 174.18 g/mol.
6. What is the difference between monopotassium phosphate and dipotassium phosphate?
The main difference is that monopotassium phosphate contains one potassium ion, while dipotassium phosphate contains two.
Comparison:
- Monopotassium phosphate: KH2PO4 (acidic salt)
- Dipotassium phosphate: K2HPO4 (weakly basic salt)
Monopotassium phosphate is formed by replacing one acidic hydrogen of H3PO4, while dipotassium phosphate is formed by replacing two.
7. Why is dipotassium phosphate used as a buffer?
Dipotassium phosphate is used as a buffer because it forms a conjugate acid–base pair with KH2PO4, resisting pH changes.
The buffer system involves:
- H2PO4- (acid form)
- HPO42- (base form)
Equilibrium:
H2PO4-(aq) ⇌ HPO42-(aq) + H+(aq)
This phosphate buffer system is widely used in biological and laboratory solutions to maintain a stable pH.
8. Is dipotassium phosphate soluble in water?
Yes, dipotassium phosphate (K2HPO4) is highly soluble in water.
When dissolved, it dissociates completely:
K2HPO4(s) → 2K+(aq) + HPO42-(aq)
Its high solubility makes it suitable for use in aqueous buffer solutions, fertilizers, and food processing applications.
9. What are the common uses of dipotassium phosphate?
Dipotassium phosphate is commonly used as a fertilizer, buffering agent, and food additive.
Major uses include:
- Fertilizers – source of potassium and phosphorus nutrients
- Buffer solutions – maintaining pH in biochemical experiments
- Food industry (E340) – acidity regulator and emulsifier
- Laboratory reagent – preparing phosphate buffer systems
Its chemical stability and solubility make it valuable in both industrial and laboratory chemistry.
10. How do you calculate the concentration of a dipotassium phosphate solution?
You calculate the concentration of a dipotassium phosphate solution using the formula M = \(\frac{n}{V}\), where M is molarity, n is moles, and V is volume in liters.
Steps:
- Calculate moles: n = mass ÷ molar mass (174.18 g/mol).
- Measure solution volume in liters.
- Substitute into M = n/V.
Example: If 17.418 g of K2HPO4 is dissolved in 1.0 L of solution:
n = 17.418 ÷ 174.18 = 0.100 mol
M = 0.100 ÷ 1.0 = 0.100 M.
