Dihydrogen Phosphate Ion

Definition

The dihydrogen phosphate ion, also known as the monohydrogen phosphate ion, is a polyatomic ion with the chemical formula H2PO4−. It is an important component in the regulation of acid-base balance within the body's physiological systems.

5 Must Know Facts For Your Next Test

1. The dihydrogen phosphate ion acts as a key buffer in the body's pH regulation, helping to maintain a stable and slightly alkaline blood pH.
2. It is involved in the regulation of the body's acid-base balance by participating in the phosphate buffer system, which helps neutralize excess hydrogen ions (H+).
3. The dihydrogen phosphate ion can accept a proton (H+) to form phosphoric acid (H3PO4) or release a proton to form the hydrogen phosphate ion (HPO4^2-).
4. The relative concentrations of the dihydrogen phosphate ion, hydrogen phosphate ion, and phosphoric acid depend on the pH of the solution, as determined by the Henderson-Hasselbalch equation.
5. The dihydrogen phosphate ion is also important in the regulation of renal (kidney) acid-base homeostasis, as it is the primary phosphate species reabsorbed and secreted by the kidneys.

Review Questions

• Explain the role of the dihydrogen phosphate ion in the body's acid-base balance.
  • The dihydrogen phosphate ion, H2PO4−, plays a crucial role in the body's acid-base balance by acting as a key component of the phosphate buffer system. This buffer system helps neutralize excess hydrogen ions (H+) in the body, maintaining a slightly alkaline blood pH of around 7.4. The dihydrogen phosphate ion can accept a proton to form phosphoric acid (H3PO4) or release a proton to form the hydrogen phosphate ion (HPO4^2-), depending on the pH of the solution. This buffering capacity is essential for regulating the body's acid-base homeostasis and preventing potentially harmful fluctuations in pH.
• Describe how the relative concentrations of the dihydrogen phosphate ion, hydrogen phosphate ion, and phosphoric acid are influenced by pH.
  • The relative concentrations of the dihydrogen phosphate ion (H2PO4−), hydrogen phosphate ion (HPO4^2−), and phosphoric acid (H3PO4) are determined by the pH of the solution, as described by the Henderson-Hasselbalch equation. At a pH of 7.4, which is the normal blood pH, the dihydrogen phosphate ion and hydrogen phosphate ion are present in roughly equal concentrations, allowing the phosphate buffer system to effectively regulate acid-base balance. As the pH decreases (becomes more acidic), the concentration of the dihydrogen phosphate ion increases, and as the pH increases (becomes more alkaline), the concentration of the hydrogen phosphate ion increases. Understanding this pH-dependent equilibrium is crucial for comprehending the dihydrogen phosphate ion's role in maintaining the body's acid-base homeostasis.
• Analyze the significance of the dihydrogen phosphate ion in the regulation of renal (kidney) acid-base homeostasis.
  • The dihydrogen phosphate ion is essential for the regulation of renal (kidney) acid-base homeostasis. The kidneys play a vital role in maintaining the body's pH by reabsorbing and secreting various ions, including the dihydrogen phosphate ion. The dihydrogen phosphate ion is the primary phosphate species reabsorbed and secreted by the kidneys, allowing them to adjust the body's phosphate levels and contribute to the overall acid-base balance. When the body experiences an excess of acid, the kidneys increase the secretion of the dihydrogen phosphate ion, which can then combine with hydrogen ions to form phosphoric acid, effectively neutralizing the excess acid. Conversely, when the body is too alkaline, the kidneys increase the reabsorption of the dihydrogen phosphate ion, reducing its availability to participate in the phosphate buffer system. This dynamic regulation of the dihydrogen phosphate ion by the kidneys is essential for maintaining the body's delicate acid-base equilibrium.

Related terms

Phosphate:

Phosphate is a polyatomic ion with the chemical formula PO4^3−, consisting of one phosphorus atom covalently bonded to four oxygen atoms.

Hydrogen Phosphate Ion:

The hydrogen phosphate ion, with the chemical formula HPO4^2−, is another important phosphate species involved in acid-base regulation.

Phosphoric Acid: Phosphoric acid, with the chemical formula H3PO4, is the triprotic acid form of phosphate and plays a crucial role in buffering systems.