The formula for sodium phosphate:
A. NaPO₄
B. Na(PO4)3
C. Na₃PO₄.
The Correct Answer and Explanation is:
The correct formula for sodium phosphate is C. Na₃PO₄.
Explanation
Sodium phosphate is a chemical compound composed of sodium ions and phosphate ions. The phosphate ion (PO₄³⁻) carries a -3 charge, meaning it can bond with three sodium ions (Na⁺), each of which has a +1 charge. This stoichiometric relationship is critical in determining the correct chemical formula for the compound.
To break it down further:
- Ionic Charges: The phosphate ion has a charge of -3, while the sodium ion has a charge of +1. Therefore, to balance the overall charge of the compound to zero (as required for stable ionic compounds), we need three sodium ions to neutralize one phosphate ion:
- (3 \times (+1) + (-3) = 0)
- Combining the Ions: Given the need for three sodium ions to balance one phosphate ion, the formula becomes Na₃PO₄. This indicates that for every one phosphate ion, there are three sodium ions.
- Common Usage: Sodium phosphate is commonly used in various applications, including food processing, as a buffering agent in laboratory settings, and in pharmaceuticals. It is available in various forms, such as monosodium phosphate (NaH₂PO₄) and disodium phosphate (Na₂HPO₄), each differing by the number of sodium ions and their resultant properties and uses.
- Molecular Weight: The molecular weight of sodium phosphate can be calculated as follows:
- Sodium (Na): 22.99 g/mol (3 × 22.99 g/mol = 68.97 g/mol)
- Phosphorus (P): 30.97 g/mol
- Oxygen (O): 16.00 g/mol (4 × 16.00 g/mol = 64.00 g/mol)
- Total molecular weight of Na₃PO₄ = 68.97 g/mol + 30.97 g/mol + 64.00 g/mol = 163.94 g/mol.
In summary, Na₃PO₄ accurately represents sodium phosphate, reflecting its composition of three sodium ions and one phosphate ion, establishing its importance in chemistry and various industries.