Problem 71 - Chemistry: An Atoms-Focused Approach

Question

How many moles of iron are there in 1 mole of the following compounds? (a) \(\mathrm{FeO} ;\) (b) \(\mathrm{Fe}_{2} \mathrm{O}_{3} ;\) (c) \(\mathrm{Fe}(\mathrm{OH})_{3}\) (d) \(\mathrm{Fe}_{3} \mathrm{O}_{4}\)

Step-by-Step Solution

Answer

Answer: (a) 1 mole of iron, (b) 2 moles of iron, (c) 1 mole of iron, and (d) 3 moles of iron.

Step 1: (a) Finding moles of iron in FeO

In FeO, there is 1 mole of iron (Fe) and 1 mole of oxygen (O) in one mole of the compound. Therefore, there is 1 mole of iron in 1 mole of FeO.

Step 2: (b) Finding moles of iron in Fe2O3

In Fe2O3, there are 2 moles of iron (Fe) and 3 moles of oxygen (O) in one mole of the compound. Therefore, there are 2 moles of iron in 1 mole of Fe2O3.

Step 3: (c) Finding moles of iron in Fe(OH)3

In Fe(OH)3, there is 1 mole of iron (Fe) and 3 moles of hydroxide ions (OH-) in one mole of the compound. Therefore, there is 1 mole of iron in 1 mole of Fe(OH)3.

Step 4: (d) Finding moles of iron in Fe3O4

In Fe3O4, there are 3 moles of iron (Fe) and 4 moles of oxygen (O) in one mole of the compound. Therefore, there are 3 moles of iron in 1 mole of Fe3O4.

Key Concepts

Understanding Chemical Compounds

Chemical compounds are substances made up of two or more different elements that are chemically bonded together. These elements combine in fixed ratios to form a distinct substance. For example, table salt (NaCl) is a chemical compound consisting of sodium and chlorine.
In our everyday life, compounds are everywhere. They can be simple, like water ( H_2O), or more complex, like the minerals found in rocks and ores. Each compound has unique properties that are different from the individual elements they contain.

• Elements in compounds are bonded together by ionic or covalent bonds.
• Compounds are described using chemical formulas which indicate the types and numbers of atoms involved.

Understanding the basics of chemical compounds is essential for studying how different substances interact, as well as in applications like pharmaceuticals, materials science, and environmental science.

Calculating Iron Content in Compounds

Iron content in compounds is an important measure in fields like metallurgy, geology, and nutrition. To find the amount of iron in a compound, we look at the chemical formula, which tells us how many moles of iron are present.
For instance, consider the exercise provided, where different iron compounds are analyzed:

• In FeO, there is one mole of iron in the compound.
• In Fe_2O_3, there are two moles of iron.
• In Fe(OH)_3, there is one mole of iron.
• In Fe_3O_4, there are three moles of iron.

These calculations help in determining the usefulness of a compound for various industrial applications, as well as in assessing nutritional content of foods that contain iron.

Understanding Molecular Composition

Molecular composition refers to the exact number of atoms of each element in a molecule. This is depicted through chemical formulas, where symbols and subscripts indicate the composition.
Consider a molecule such as Fe_2O_3, found in nature as hematite, a common ore of iron. Its formula shows:

• 2 atoms of iron (Fe)
• 3 atoms of oxygen (O)

The subscript numbers give the precise count of atoms, which is crucial when calculating molar ratios in reactions or analyzing the properties of a substance.

• Molecular composition provides insight into a compound's properties and behavior during chemical reactions.
• Knowing the molecular composition is key to manufacturing processes, where specific compounds need to be synthesized.

In summary, understanding the molecular composition of a compound helps in various scientific and industrial applications by predicting how it will react under different conditions.