What is the name of the compound (NH4)3PO3? Why is special about this compound? Choose one answer.
a. Ammonium phosphate; this covalent compound is made up of two polyatomic ions, ammonium and phosphate.
b. Ammonium phosphite; this ionic compound is made up of two polyatomic ions, ammonium and phosphite.
c. Ammonium phosphate; this ionic compound is made up of two polyatomic ions, ammonium and phosphate.
d. Ammonium phosphite; this covalent compound is made up of two polyatomic ions, ammonium and phosphite.
The correct answer and explanation is :
The correct answer is b. Ammonium phosphite; this ionic compound is made up of two polyatomic ions, ammonium and phosphite.
Explanation:
The compound (NH₄)₃PO₃ is composed of ammonium ions (NH₄⁺) and phosphite ions (PO₃³⁻). To understand this, let’s break down the components and naming conventions involved.
- Ammonium Ion (NH₄⁺): This is a polyatomic ion composed of nitrogen and hydrogen. The ammonium ion carries a +1 charge, and it is a common polyatomic ion found in various compounds, especially salts.
- Phosphite Ion (PO₃³⁻): The formula (PO₃) represents the phosphite ion. It is similar to the phosphate ion (PO₄³⁻), but the key difference is that phosphite contains one less oxygen atom than phosphate. Phosphite is typically less stable than phosphate and is commonly encountered in various chemical compounds, especially those in which the oxidation state of phosphorus is +3, as opposed to +5 in phosphate.
The formula (NH₄)₃PO₃ indicates that three ammonium ions (NH₄⁺) balance the charge of one phosphite ion (PO₃³⁻), resulting in a neutral compound. This is an ionic compound because it involves electrostatic attraction between the positively charged ammonium ions and the negatively charged phosphite ions.
Special Characteristics:
- The name ammonium phosphite reflects the presence of ammonium as the cation and phosphite as the anion. Phosphite is distinct from phosphate, which has four oxygen atoms rather than three, and is usually encountered in compounds where phosphorus is in a higher oxidation state (+5).
- This compound is ionic because it consists of a metal-like cation (ammonium) and a non-metal-like anion (phosphite), and the electrostatic forces between them hold the compound together.
Thus, the compound (NH₄)₃PO₃ is ammonium phosphite, an ionic compound made up of ammonium and phosphite ions.