About Ammonium Phosphate
Ammonium phosphate is a salt that is made up of ammonia and phosphorus, and its chemical formula is (NH4)3PO4. However, this is a very unstable salt and due to how unstable it is, it is not exactly a salt worth a lot of commercial value. It can be formed by combining phosphoric acid along with ammonia, or by adding a lot more ammonia with acid phosphate.
For it to be used commercially, it is mostly obtained from crystalline powders.
The Formula of Ammonium Phosphate
The molecular formula for this salt is (NH4)3PO4 and it is also referred to as triammonium phosphate or diazonium hydrogen phosphate.
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How is Ammonium Phosphate Formed?
When phosphoric acid H3PO4 reacts with ammonia NH3 (it needs to be anhydrous in nature), we get the following reaction:
NH3 + H3PO4 → NH4H2PO4
On combining concentrated quantities of both the products, ammonium phosphate is amassed in the form of a crystallised powder. This powder is soluble in water and if the water is boiled, then the solution loses the ammonia in the form of gas. This then results in the formation of acid phosphate (NH4)(H2PO4).
Structure of Ammonium Phosphate
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What are the Properties of Ammonium Phosphate?
Every salt or compound has a set of distinct physical and chemical properties which are used as basic determinants to differentiate it from other chemical compounds and salts.
Physical Properties:
Since this is a salt of ammonia, the characteristic smell of ammonia will always be present. The crystallised powder is white in colour. The powder is also very easily soluble in water with a pH that ranges between 4-4.5.
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Chemical Properties:
The salt is highly unstable due to the nature of the compounds that are combined to make this.
Even though triammonium salt has an unstable nature, diammonium phosphate still holds an important position within the fertilizer industry. That being said, all the phosphate acids are divided into three categories:
Phosphoric acid and super phosphoric acid
Normal superphosphate and triple superphosphate
Ammonium phosphate in granular form
Ammonium phosphate can readily react with lead nitrate, which results in the formation of ammonium nitrate and lead phosphate.
4(NH4)3PO4 + 3Pb(NO3)4 → Pb3(PO4)4 + 12NH4NO3
Anhydrous ammonia, when it reacts with phosphoric acid, also results in the production of the ammonium phosphate.
NH3 + H3PO4 à NH4H2PO4
Ammonium Phosphate Uses
Down below is a list of some of the major use cases of ammonium phosphate:
Ammonium phosphate is used as a leavening agent during the process of bakingIts interaction with heat, results in instant evaporation without leaving any residue of ammonia
Due to the ability of rapidly dissolving and becoming soluble, ammonium phosphate works as an effective fertilizer. It has two crucial elements embedded in them, the ammonium and phosphate, both of which are highly beneficial to the plants
It also works great as a plant revitalize
Ammonium phosphate can also be used as a great ingredient for dry chemical extinguisher
Solved Questions
1. If a sample of Ammonium phosphate (NH4)3PO4 has 3.18 moles of hydrogen atom then what is the number of moles available for oxygen atoms within the solution?
i) 0.265
ii) 1.06
iii) 0.795
iv) 3.18
Solution: As we know that the molar mass of (NH4)3PO4 is 149 grams.
Within the same, contains 12 g of HSo for 3.18 moles, i.e. 3.18 grams of H, the total number of moles of ammonium phosphate:
12149×3.18=39.5gm (NH4)3PO4
We know that 149 grams of (NH4)3PO4 contains 64g of oxygen
So, for 39.5 grams of (NH4)3PO4 it will contain
14964×39.5g of oxygen =16.96 gm oxygen
So, 16.96 grams of oxygen is present
Converting it into moles, we get, 1616.96 = 1.06 moles of OSo, the right answer is option ii).
2. If 6 moles of H are present in a sample of (NH4)3PO4, what is the number of moles of oxygen atom? Answer the question without converting the moles into grams.
1) 6
2) 4
3) 2
4) 1
Solution: We know that in ammonium phosphate:
The total number of H atoms: 12
Total number of O atoms: 4
We know that the ratio of atoms and moles remains the same
So, 12/4 = 6/X
Or, X = 2
So, the total number of moles of oxygen is 2.
FAQs on Ammonium Phosphate - Formula, Structure, Properties and Uses
1. What exactly is ammonium phosphate and what is its chemical formula?
Ammonium phosphate is an inorganic salt formed from the reaction of ammonia and phosphoric acid. Its chemical formula is (NH₄)₃PO₄. It is a white, crystalline solid that is highly important in agriculture and various industries. It primarily consists of ammonium cations (NH₄⁺) and phosphate anions (PO₄³⁻).
2. What are the main physical and chemical properties of ammonium phosphate?
Ammonium phosphate has several distinct properties that make it useful. Key characteristics include:
- Appearance: It is typically a white, odourless, crystalline powder.
- Solubility: It is highly soluble in water but insoluble in ethanol.
- Stability: The compound is unstable and tends to decompose upon heating, releasing ammonia gas.
- pH: When dissolved in water, it forms a mildly acidic or basic solution depending on the specific type (e.g., monoammonium or diammonium phosphate).
3. Why is ammonium phosphate so effective as a fertilizer?
Ammonium phosphate is an excellent fertilizer because it supplies two essential nutrients for plant growth in a single compound: nitrogen (N) from the ammonium ion and phosphorus (P) from the phosphate ion. Since it is water-soluble, these nutrients are easily and quickly absorbed by plant roots, promoting strong root development, vibrant foliage, and healthy flowering.
4. What is the basic difference between an ammonia molecule and an ammonium ion?
The main difference lies in their chemical structure and charge. Ammonia (NH₃) is a neutral molecule with one nitrogen atom bonded to three hydrogen atoms. In contrast, the ammonium ion (NH₄⁺) is a positively charged cation, formed when ammonia accepts a proton (H⁺). This positive charge allows it to form ionic bonds with anions like phosphate to create salts.
5. How can the formula for ammonium phosphate be derived using the criss-cross method?
You can determine the formula step-by-step:
- First, identify the two ions involved: Ammonium is NH₄⁺ and Phosphate is PO₄³⁻.
- Note their valencies (charges): Ammonium has a charge of +1, and Phosphate has a charge of -3.
- Next, 'criss-cross' the numerical values of these charges, making them the subscripts for the opposite ion. The '3' from phosphate becomes the subscript for ammonium, and the '1' from ammonium becomes the subscript for phosphate.
- This gives us (NH₄)₃(PO₄)₁. Since a subscript of 1 is never written, the final formula is (NH₄)₃PO₄.
6. Besides fertilizers, what are some other important uses for ammonium phosphate?
While its primary application is in agriculture, ammonium phosphate is also used in other areas. It is used as a fire retardant in firefighting products, as it releases water and ammonia gas when heated, which smothers flames. It can also be found in some food products as a leavening agent and a pH control agent.
7. Why is ammonium phosphate so easily dissolved in water?
Ammonium phosphate dissolves easily in water because it is an ionic compound and water is a polar solvent. The positive hydrogen ends of water molecules are attracted to the negatively charged phosphate ions (PO₄³⁻), and the negative oxygen ends are attracted to the positively charged ammonium ions (NH₄⁺). This attraction is strong enough to pull the ions apart from the crystal lattice and into the solution.
8. What happens when ammonium phosphate is heated?
When ammonium phosphate is heated, it undergoes thermal decomposition. It breaks down into ammonia gas (NH₃) and phosphoric acid (H₃PO₄). Because it is not a very stable compound, this decomposition can happen at relatively moderate temperatures. This is one reason why it is effective as a fire retardant, as the process smothers fire.
