Question

Write a chemical equation that represents ( \(\left.\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}(\mathrm{~s})\) dissociating in water.

Short answer

The dissociation equation is: \((\mathrm{NH}_{4})_3\mathrm{PO}_4 (\mathrm{s}) \rightarrow 3\mathrm{NH}_4^+ (\mathrm{aq}) + \mathrm{PO}_4^{3-} (\mathrm{aq})\).

Step-by-step solution

Write the Formula for Dissociation

To write the chemical equation representing the dissociation, you need to start with the formula for ammonium phosphate, \((\mathrm{NH}_4)_3\mathrm{PO}_4(\mathrm{s})\). This solid compound will dissociate into its ions when it is dissolved in water.

Identify the Component Ions

The formula \((\mathrm{NH}_4)_3\mathrm{PO}_4\) indicates that the compound is made of ammonium ions \((\mathrm{NH}_4^+)\) and phosphate ions \((\mathrm{PO}_4^{3-})\). Each molecule supplies three ammonium ions and one phosphate ion when dissolved.

Balance the Chemical Equation

For the dissociation, write the equation with the solid compound on the left-hand side and the ions on the right.\[\left(\mathrm{NH}_{4}\right)_{3}\mathrm{PO}_{4}(\mathrm{s}) \rightarrow 3\mathrm{NH}_{4}^{+}(\mathrm{aq}) + \mathrm{PO}_{4}^{3-}(\mathrm{aq})\]Ensure that the number of atoms and charge are balanced.

Key concepts

Chemical Equation

A chemical equation is like a recipe. It shows which substances you start with (the reactants) and what you end up with (the products) in a chemical reaction.
It is a symbolic way to represent a chemical reaction using element symbols and chemical formulas. In a balanced chemical equation, you'll find the same number of each type of atom on both sides of the equation. This balance reflects the law of conservation of mass, which states that matter cannot be created or destroyed in an isolated system.

When writing a chemical equation for a dissociation reaction, like for ammonium phosphate, it's essential to remember:

• The reactants are the original compounds before dissociation.
• The products are the ions that form when the compound dissolves in water.

Balancing means making sure both sides of the chemical equation reflect the same number of each type of atom and charge. This step is crucial because in the reaction, atoms and charge must be conserved. Balancing chemical equations is an important skill as it ensures that the reaction equation accurately represents what's happening in the reaction itself.

Ammonium Phosphate

Ammonium phosphate, with the chemical formula \((\mathrm{NH}_4)_3\mathrm{PO}_4\), is a common compound often used as a fertilizer because it provides essential nutrients like nitrogen and phosphorus to plants.
It appears as a white, crystalline solid and contains two main types of ions:

• Ammonium ions \((\mathrm{NH}_4^+)\).
• Phosphate ions \((\mathrm{PO}_4^{3-})\).

When this compound dissolves in water, it separates into these ions. Understanding the makeup of ammonium phosphate is key to writing the chemical equation for its dissociation.
By knowing it contains three ammonium ions and one phosphate ion per molecule, you can then write a balanced equation that properly shows the dissociation process.

Ionization in Water

Ionization in water refers to the process where molecules separate into ions when dissolved. A great number of ionic compounds, like ammonium phosphate, dissociate in water.

The aqueous state, often symbolized by \(\mathrm{(aq)}\), indicates that the ions are dissolved in water, allowing them to move freely. This freedom is why reactions in water are special — ions can easily interact with one another.
Understanding ionization is crucial because:

• It helps explain conductivity in solutions. Dissolved ions allow water to conduct electricity.
• Shows how substances dissolve and recombine in water to form new products during chemical reactions.

In the case of ammonium phosphate, ionization in water means the solid compound breaks down to produce three ammonium ions and one phosphate ion for each formula unit that dissolves.