Ch.3 - Mass Relationships in Chemical Reactions

McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook

McMurry 8th Edition

Ch.3 - Mass Relationships in Chemical Reactions

Problem 89

Chapter 3, Problem 89

Ferrocene, a substance proposed for use as a gasoline additive, has the percent composition 5.42% H, 64.56% C, and 30.02% Fe. What is the empirical formula of ferrocene?

Verified step by step guidance

Assume you have 100 grams of ferrocene, which allows you to directly convert the percentage of each element to grams: 5.42 g of H, 64.56 g of C, and 30.02 g of Fe.

Convert the mass of each element to moles by dividing by their respective molar masses: \( \text{H: } \frac{5.42 \text{ g}}{1.01 \text{ g/mol}} \), \( \text{C: } \frac{64.56 \text{ g}}{12.01 \text{ g/mol}} \), \( \text{Fe: } \frac{30.02 \text{ g}}{55.85 \text{ g/mol}} \).

Determine the mole ratio of the elements by dividing each element's mole value by the smallest number of moles calculated in the previous step.

Round the mole ratios to the nearest whole number to find the subscripts for each element in the empirical formula.

Write the empirical formula using the whole number mole ratios as subscripts for each element.

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Key Concepts

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

Percent Composition

Percent composition refers to the percentage by mass of each element in a compound. It is calculated by dividing the mass of each element in a sample by the total mass of the compound and multiplying by 100. Understanding percent composition is essential for determining the relative amounts of each element, which is a crucial step in finding the empirical formula.

Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present. It is derived from the percent composition by converting the percentages to moles and then simplifying the mole ratios. This formula provides insight into the basic structure of the compound without detailing the actual number of atoms in a molecule.

Mole Concept

The mole concept is a fundamental principle in chemistry that relates the mass of a substance to the number of particles it contains. One mole of any substance contains Avogadro's number (approximately 6.022 x 10^23) of entities, whether they are atoms, molecules, or ions. This concept is crucial for converting percent composition to moles, which is necessary for calculating the empirical formula.

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