Tripotassium Phosphate vs. Trisodium Phosphate

What's the Difference?

Tripotassium phosphate and trisodium phosphate are both inorganic compounds commonly used in various industrial and household applications. However, they differ in terms of their chemical composition and properties. Tripotassium phosphate, with the chemical formula K3PO4, is a white crystalline powder that is highly soluble in water. It is primarily used as a food additive, buffering agent, and fertilizer. On the other hand, trisodium phosphate, with the chemical formula Na3PO4, is also a white crystalline powder but is less soluble in water compared to tripotassium phosphate. Trisodium phosphate is commonly used as a cleaning agent, degreaser, and stain remover. Overall, while both compounds have their own specific uses, tripotassium phosphate is more commonly found in food-related applications, while trisodium phosphate is often used for cleaning purposes.


AttributeTripotassium PhosphateTrisodium Phosphate
SynonymsPotassium phosphate tribasic, Tripotassium orthophosphateSodium phosphate tribasic, Trisodium orthophosphate
Chemical FormulaK3PO4Na3PO4
Molar Mass212.27 g/mol163.94 g/mol
AppearanceWhite crystalline powderWhite crystalline powder
SolubilitySoluble in waterSoluble in water
pH LevelBasicBasic
Common UsesFood additive, fertilizer, buffering agentFood additive, cleaning agent, water treatment

Further Detail


When it comes to phosphates, two commonly used compounds are tripotassium phosphate (K3PO4) and trisodium phosphate (Na3PO4). These chemicals find applications in various industries, including food, cleaning, and agriculture. While both compounds contain phosphorus and are used for similar purposes, they differ in terms of their properties and specific applications. In this article, we will explore the attributes of tripotassium phosphate and trisodium phosphate, highlighting their differences and similarities.

Chemical Composition

Tripotassium phosphate, as the name suggests, consists of three potassium (K) ions bonded to a phosphate (PO4) group. Its chemical formula is K3PO4. On the other hand, trisodium phosphate is composed of three sodium (Na) ions bonded to a phosphate group, with a chemical formula of Na3PO4. The primary distinction between the two compounds lies in the cationic component, with tripotassium phosphate containing potassium ions and trisodium phosphate containing sodium ions.

Solubility and pH

Both tripotassium phosphate and trisodium phosphate are highly soluble in water. However, their solubility varies slightly due to the different ionic strengths of potassium and sodium. Tripotassium phosphate has a solubility of approximately 110 g/100 mL of water at room temperature, while trisodium phosphate has a solubility of around 70 g/100 mL. This difference in solubility can be attributed to the varying hydration energies of the potassium and sodium ions.

Regarding pH, tripotassium phosphate and trisodium phosphate exhibit different effects when dissolved in water. Tripotassium phosphate is an alkaline compound and acts as a pH buffer, helping to maintain a stable pH level in solutions. It has a basic pH of around 11.5. On the other hand, trisodium phosphate is also alkaline but has a higher pH of approximately 12.5. This higher pH makes trisodium phosphate more effective as a cleaning agent, especially in removing grease and oil.


Tripotassium Phosphate:

1. Food Industry: Tripotassium phosphate is commonly used as a food additive, primarily as a pH regulator and emulsifier. It helps stabilize the acidity of certain food products, such as dairy and meat products. Additionally, it acts as an emulsifier in processed foods, preventing the separation of oil and water-based ingredients.

2. Agriculture: Tripotassium phosphate is also utilized in agriculture as a source of potassium and phosphorus. It serves as a fertilizer, providing essential nutrients to plants for healthy growth and development.

3. Industrial Applications: In various industrial processes, tripotassium phosphate finds applications as a buffering agent, corrosion inhibitor, and dispersing agent. It helps control pH levels, prevents metal corrosion, and aids in the dispersion of particles in solutions.

Trisodium Phosphate:

1. Cleaning Products: Trisodium phosphate is widely used in cleaning products, including detergents and degreasers. Its high alkalinity and ability to break down grease make it effective in removing tough stains and residues from surfaces.

2. Paint and Surface Preparation: Trisodium phosphate is utilized in the preparation of surfaces before painting. It helps remove dirt, grime, and old paint, ensuring a clean and smooth surface for better paint adhesion.

3. Water Treatment: Trisodium phosphate is employed in water treatment processes to adjust pH levels and remove contaminants. It aids in the removal of calcium and magnesium ions, preventing scale formation in pipes and equipment.

Safety Considerations

While both tripotassium phosphate and trisodium phosphate are generally considered safe for their intended applications, it is important to handle them with care and follow proper safety precautions.

1. Tripotassium Phosphate: This compound may cause skin and eye irritation upon direct contact. It is advisable to wear protective gloves and goggles when handling tripotassium phosphate. Ingestion should be avoided, and accidental ingestion should be immediately addressed by seeking medical attention.

2. Trisodium Phosphate: Similar to tripotassium phosphate, trisodium phosphate can cause skin and eye irritation. It is recommended to use protective equipment when working with trisodium phosphate. Ingestion should be avoided, and any accidental ingestion should be treated by seeking medical assistance.


In summary, tripotassium phosphate and trisodium phosphate are two phosphate compounds with distinct properties and applications. While tripotassium phosphate contains potassium ions and is commonly used in the food industry and agriculture, trisodium phosphate contains sodium ions and finds applications in cleaning products, surface preparation, and water treatment. Understanding the differences between these compounds allows for their appropriate use in various industries, ensuring optimal results and safety.

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