Ch.3 - Chemical Reactions and Reaction Stoichiometry

Brown - Chemistry: The Central Science 15th Edition

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Brown 15th Edition

Ch.3 - Chemical Reactions and Reaction Stoichiometry

Problem 45a

Chapter 3, Problem 45a

Give the empirical formula of each of the following compounds if a sample contains a.0.0130 mol C, 0.0390 mol H, and 0.0065 mol O

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Identify the number of moles of each element in the compound: 0.0130 mol C, 0.0390 mol H, and 0.0065 mol O.

Divide the number of moles of each element by the smallest number of moles present among the elements to find the simplest whole number ratio. In this case, divide each by 0.0065 mol.

Calculate the resulting ratios: \( \frac{0.0130}{0.0065} \) for C, \( \frac{0.0390}{0.0065} \) for H, and \( \frac{0.0065}{0.0065} \) for O.

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

Write the empirical formula using the whole number 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.

Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present in that compound. It is derived from the mole quantities of each element, providing a basic understanding of the composition without indicating the actual number of atoms in a molecule.

Mole Concept

The mole is a fundamental unit in chemistry that quantifies the amount of substance. One mole corresponds to approximately 6.022 x 10²³ entities (atoms, molecules, etc.). Understanding the mole concept is essential for converting between mass, number of particles, and volume in chemical calculations.

Mole Ratio

Mole ratio is the ratio of the number of moles of one substance to the number of moles of another substance in a chemical reaction or mixture. It is crucial for determining the empirical formula, as it allows for the simplification of the mole quantities of each element to their smallest whole-number ratio.

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