what is the chemical formula for hydrogen phosphate
The Correct Answer and Explanation is:
Chemical Formula for Hydrogen Phosphate:
The chemical formula for hydrogen phosphate is HPO₄²⁻.
Textbook-Style Explanation:
Hydrogen phosphate is an anion derived from phosphoric acid (H₃PO₄). When phosphoric acid loses two of its three acidic hydrogen ions (protons), it forms the hydrogen phosphate ion. The name “hydrogen phosphate” indicates the presence of one hydrogen atom and a phosphate group with an overall –2 charge.
Phosphoric acid is a triprotic acid, meaning it has three dissociable hydrogen atoms:
- The first dissociation produces dihydrogen phosphate (H₂PO₄⁻).
- The second dissociation yields hydrogen phosphate (HPO₄²⁻).
- The third dissociation results in phosphate (PO₄³⁻).
These dissociation steps are:
- H₃PO₄ ⇌ H⁺ + H₂PO₄⁻
- H₂PO₄⁻ ⇌ H⁺ + HPO₄²⁻
- HPO₄²⁻ ⇌ H⁺ + PO₄³⁻
The hydrogen phosphate ion (HPO₄²⁻) is formed in the second step, where one more hydrogen ion is lost from dihydrogen phosphate.
Hydrogen phosphate consists of:
- 1 hydrogen atom (H)
- 1 phosphorus atom (P)
- 4 oxygen atoms (O)
This gives the molecular formula HPO₄, and the ion carries a –2 charge because it has gained two electrons through the loss of two protons from the parent acid.
This ion is often found in biological systems, especially in buffer solutions where it plays a role in maintaining pH balance. It is also a component of various salts such as sodium hydrogen phosphate (Na₂HPO₄) and calcium hydrogen phosphate (CaHPO₄).
Understanding hydrogen phosphate and its related ions is essential in fields like chemistry, biology, medicine, and environmental science, where phosphate buffering systems are crucial.
