Ch.2 - Atoms, Molecules, and Ions

Brown - Chemistry: The Central Science 15th Edition

Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook

Brown 15th Edition

Ch.2 - Atoms, Molecules, and Ions

Problem 62e

Chapter 2, Problem 62e

Predict the chemical formulas of the compounds formed by the following pairs of ions: (e) NH4+ and PO43-.

Verified step by step guidance

Identify the charges on each ion: \( \text{NH}_4^+ \) has a charge of +1 and \( \text{PO}_4^{3-} \) has a charge of -3.

Determine the ratio of ions needed to balance the charges. You need enough \( \text{NH}_4^+ \) ions to balance the -3 charge of \( \text{PO}_4^{3-} \).

To balance the charges, use 3 \( \text{NH}_4^+ \) ions for every 1 \( \text{PO}_4^{3-} \) ion, resulting in a neutral compound.

Write the chemical formula by placing the number of each ion as a subscript: \( (\text{NH}_4)_3\text{PO}_4 \).

Verify that the total positive charge from the \( \text{NH}_4^+ \) ions equals the total negative charge from the \( \text{PO}_4^{3-} \) ion, ensuring the compound is neutral.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

46s

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ionic Compounds

Ionic compounds are formed when positively charged ions (cations) and negatively charged ions (anions) combine. The overall charge of the compound must be neutral, meaning the total positive charge must balance the total negative charge. Understanding how to combine these ions based on their charges is essential for predicting the correct chemical formula.

Polyatomic Ions

Polyatomic ions are ions that consist of two or more atoms bonded together, carrying a net charge. In this case, ammonium (NH4+) is a common polyatomic cation, while phosphate (PO43-) is a polyatomic anion. Recognizing these ions and their charges is crucial for determining how they interact to form compounds.

Charge Balance

Charge balance is the principle that the total positive charge in a compound must equal the total negative charge. For the ions NH4+ and PO43-, the ammonium ion has a +1 charge and the phosphate ion has a -3 charge. To achieve charge neutrality, three ammonium ions would be needed to balance one phosphate ion, leading to the formula (NH4)3PO4.

Recommended video:

Guided course

01:53

Formal Charge

Related Practice

Textbook Question

Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair. Ion Na+ Ca2+ Fe2+ Al3+ O2- Na2O NO3- SO42- AsO43-

Textbook Question

Predict the chemical formulas of the compounds formed by the following pairs of ions: (b) Fe3+ and O2-

Textbook Question

Predict the chemical formulas of the compounds formed by the following pairs of ions: (c) Hg22+ and CO32-

Textbook Question

Predict the chemical formulas of the compounds formed by the following pairs of ions: (d) Ca2+ and ClO3-

Textbook Question

Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair. Ion K⁺ NH₄⁺ Mg²⁺ Fe³⁺ Cl^- KCl OH^- CO₃^2- PO₄^3-

Complete the first row of the table.

Complete the second row of the table.

Complete the third row of the table.

Complete the fourth row of the table.

Textbook Question

Predict whether each of the following compounds is molecular or ionic: (a) B2H6