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

Verified step by step guidance

Identify the charges of the ions: Fe^{3+} has a charge of +3 and O^{2-} has a charge of -2.

To form a neutral compound, the total positive charge must balance the total negative charge.

Determine the least common multiple (LCM) of the charges: The LCM of 3 and 2 is 6.

Calculate the number of each ion needed to achieve charge balance: You need 2 Fe^{3+} ions (2 x +3 = +6) and 3 O^{2-} ions (3 x -2 = -6).

Write the chemical formula by placing the number of each ion as subscripts: Fe_2O_3.

Verified video answer for a similar problem:

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

Video duration:

28s

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.

Charge Balance

Charge balance is a fundamental principle in chemistry that dictates how ions combine to form neutral compounds. For example, in the case of Fe3+ (a cation with a +3 charge) and O2- (an anion with a -2 charge), the charges must be balanced to achieve neutrality. This often involves determining the lowest common multiple of the charges to find the correct ratio of ions.

Chemical Formula Representation

The chemical formula of a compound represents the types and numbers of atoms present in the compound. For ionic compounds, the formula is typically written with the cation first followed by the anion, and subscripts are used to indicate the number of each ion needed to achieve charge balance. For example, the formula for the compound formed by Fe3+ and O2- is Fe2O3, indicating two iron ions and three oxide ions.

Recommended video:

Guided course

02:08

Molecular Formula

Related Practice

Textbook Question

Predict the chemical formula for the ionic compound formed by (c) Al3+ and CH3COO-

Textbook Question

Predict the chemical formula for the ionic compound formed by (d) NH4+ and SO42-

Textbook Question

Predict the chemical formula for the ionic compound formed by (e) Mg2+ and PO43-.

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

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