What Is Calcium Phosphate Definition Formula Preparation Reactions and Uses
Calcium phosphate can be described as a calcium salt of phosphoric acid having a chemical formula, as Ca3(PO4)2. It can also be called Tricalcium Phosphate or Calcium phosphate tribasic.
Calcium phosphate compound appears to be either crystalline or white amorphous powder that is tasteless and odorless. It is insoluble in acetic acid and ethanol but soluble in hydrochloric acid and dilute nitric acid. Also, it slightly dissolves in water and is found in milk, bones, teeth, and ground.
Characteristics of Calcium Phosphate
Apatite is a mineral rock that is a complex and impure form of calcium phosphate that produces tribasic calcium phosphate.
Apatite is a form of phosphorite that contains calcium phosphate, which is mixed with other compounds.
Calcium phosphates are the important materials of Geology, Biology, Medicine, Dentistry, and Industry.
Its functions, applications, and formation, depends on its composition, solubility, stability, and structure.
Calcium Phosphate Preparation
It is also produced by reacting the phosphoric acid (H3PO4) with solid calcium hydroxide Ca(OH)2.
The chemical equations can be given as below:
3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O (Balanced Equation)
Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O (Unbalanced Equation)
Dibasic-calcium phosphate is made in the calcium phosphate reaction with an aqueous solution of calcium hydroxide. In contrast, the monobasic calcium phosphate can be obtained by adding the excess phosphoric acid to either a dibasic solution or a tribasic calcium phosphate solution and permitting it to evaporate.
Structure of Ca3(PO4)2
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Properties of Calcium Phosphate - Ca3(PO4)2
Solubility of Calcium Phosphate Ca3(PO4)2
Solubility is the most important characteristic of calcium phosphate salts. Solubility can be defined by the course of various reactions involving calcium phosphates such as precipitation, hydrolysis, phase transformation, and absorption. The solubility of calcium phosphate also plays a primary role in the biological processes, including resorption, hard tissue formation, and pathological calcification.
The bone graft replacements (mostly hydroxyapatite or tricalcium phosphate) based on the calcium phosphate are bioceramics having the greatest resemblance to bone minerals. This makes the calcium phosphate excellent biodegradability, osteoconductivity, and biocompatibility.
Occurrence of Calcium Phosphate
Phosphorus and Calcium make up the bulk of animal mineral nutrient requirements (to fulfill both milk needs and body tissue). Therefore, the DCPD is a popular and commonly used animal supplement. Also, Dicalcium Phosphate Dihydrate is mainly considered because it is the most soluble of barely soluble crystals of calcium phosphate, making it a good choice for the rock phosphate dissolution tests. The DCPD fate in the soil is rather temporary.
Usually, mineral phosphorus is applied to the soil in a water-soluble form, such as diammonium phosphate or triple superphosphate. Since the phosphorus dissolves at a high concentration of a solution (suppose as ‘P’), the precipitation reactions are mostly preferred. Calcium phosphates can be found naturally in many ways, and they are the primary minerals for phosphate fertilizer manufacture and a variety of phosphorus compounds.
Health Hazards of Calcium Phosphate
When the doses of ingested toxins become more than 2 gms/kg, there is an unusual skin sensitization. Consumption of it can cause chemical pneumonitis. Also, calcium phosphate is used in most of the products in biomedicine, including cosmetics and dentistry.
It can be found in nanoparticle form in some situations, either on purpose, after mechanical abrasion, or degradation. Some possible issues are referred to as the biological impact of these nanoparticles.
An in-depth literature review represents that calcium phosphate nanoparticles, as such, do not have inherent toxicity but can lead to an intracellular calcium concentration increase following lysosomal degradation and endosomal uptake. However, within a few hours, the cells can remove calcium from the cytoplasm unless huge doses of calcium phosphate are used.
The cytotoxicity observed in a few cell culture studies, especially for the unfunctionalized particles, is likely because of the subsequent sedimentation and particle agglomeration on the cell layer, leading to very high local particle concentration, subsequent cell death, and high absorption of particles.
The nanoparticles of calcium phosphate can reach the bloodstream by inhalation. Still, there are no harmful effects that have been noticed, except for the extended exposure to doses of high particles. Whereas the nanoparticles of calcium phosphate within the body don't pose a risk since they are resorbed and destroyed normally by macrophages and osteoclasts.
FAQs on Calcium Phosphate Structure Properties and Importance in Chemistry
1. What is calcium phosphate?
Calcium phosphate is a family of inorganic compounds composed of calcium ions (Ca2+) and phosphate ions (PO43-). It commonly refers to salts such as Ca3(PO4)2 and related compounds found in bones and teeth.
Key points:
- Formed from calcium and phosphoric acid derivatives.
- Occurs naturally in rocks, bones, and teeth.
- Used in fertilizers, food additives, and biomaterials.
2. What is the chemical formula for calcium phosphate?
The chemical formula for tricalcium phosphate, the most common form of calcium phosphate, is Ca3(PO4)2.
Explanation:
- Calcium ion: Ca2+
- Phosphate ion: PO43-
- To balance charges: 3 × (+2) = +6 and 2 × (−3) = −6
- Overall neutral compound: Ca3(PO4)2
3. How is calcium phosphate formed?
Calcium phosphate is formed by reacting a soluble calcium salt with a soluble phosphate salt in a precipitation reaction.
Example balanced equation:
- 3CaCl2(aq) + 2Na3PO4(aq) → Ca3(PO4)2(s) + 6NaCl(aq)
In this reaction, insoluble calcium phosphate forms as a white precipitate.
4. Is calcium phosphate soluble in water?
Calcium phosphate (Ca3(PO4)2) is sparingly soluble in water.
Details:
- It has a very low solubility product constant (Ksp).
- Most of it remains as a solid in aqueous solution.
- It dissolves more readily in acidic solutions due to reaction with H+ ions.
Example in acid:
- Ca3(PO4)2(s) + 4H+(aq) → 3Ca2+(aq) + 2H2PO4-(aq)
5. What is the difference between calcium phosphate and hydroxyapatite?
The main difference is that calcium phosphate is a general term for Ca–PO4 salts, while hydroxyapatite is a specific compound with the formula Ca5(PO4)3OH.
Comparison:
- Calcium phosphate: Includes Ca3(PO4)2, CaHPO4, and others.
- Hydroxyapatite: Major mineral component of bones and teeth.
- Hydroxyapatite has a defined crystal structure and biological role.
6. What are the main types of calcium phosphate?
The main types of calcium phosphate include monocalcium phosphate, dicalcium phosphate, and tricalcium phosphate.
Common types:
- Monocalcium phosphate: Ca(H2PO4)2
- Dicalcium phosphate: CaHPO4
- Tricalcium phosphate: Ca3(PO4)2
- Hydroxyapatite: Ca5(PO4)3OH
They differ in Ca:P ratio, solubility, and applications in fertilizers and biomaterials.
7. What is calcium phosphate used for?
Calcium phosphate is used in fertilizers, food additives, dental products, and biomedical implants.
Major applications:
- Fertilizers: Source of phosphorus for plant growth.
- Food industry: Anti-caking agent and calcium supplement.
- Dentistry: Remineralization of enamel.
- Medical field: Bone grafts and bioceramics.
8. How do you calculate the molar mass of calcium phosphate?
The molar mass of calcium phosphate (Ca3(PO4)2) is calculated by summing the atomic masses of all atoms in the formula.
Step-by-step calculation:
- Ca: 3 × 40.08 = 120.24 g/mol
- P: 2 × 30.97 = 61.94 g/mol
- O: 8 × 16.00 = 128.00 g/mol
- Total = 310.18 g/mol
Thus, the molar mass of Ca3(PO4)2 is approximately 310.18 g/mol.
9. Why is calcium phosphate important in bones and teeth?
Calcium phosphate is important in bones and teeth because it provides hardness and structural strength in the form of hydroxyapatite.
Details:
- Bones contain crystals of Ca5(PO4)3OH.
- These crystals are embedded in a collagen matrix.
- They give bones rigidity while collagen provides flexibility.
This mineral structure makes calcium phosphate essential for skeletal health.
10. How do you write the ionic equation for the formation of calcium phosphate?
The net ionic equation for the formation of calcium phosphate is 3Ca2+(aq) + 2PO43-(aq) → Ca3(PO4)2(s).
Steps to derive it:
- Write the balanced molecular equation.
- Dissociate soluble salts into ions.
- Remove spectator ions (e.g., Na+, Cl-).
- Write the remaining species as the net ionic equation.
This represents the precipitation of insoluble calcium phosphate from aqueous solution.
