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Ch.3 - Chemical Reactions and Reaction Stoichiometry
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
All textbooksBrown 14th EditionCh.3 - Chemical Reactions and Reaction StoichiometryProblem 38a
Chapter 3, Problem 38a

(a) What is the mass, in grams, of 1.223 mol of iron(III) sulfate? (b) How many moles of ammonium ions are in 6.955 g of ammonium carbonate? (c) What is the mass, in grams, of 1.50 * 1021 molecules of aspirin, C9H8O4?

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(a) Calculate the molar mass of iron(III) sulfate, Fe2(SO4)3, by adding the atomic masses of all atoms in the formula: 2 Fe, 3 S, and 12 O.
(a) Multiply the molar mass of Fe2(SO4)3 by the number of moles (1.223 mol) to find the mass in grams.
(b) Calculate the molar mass of ammonium carbonate, (NH4)2CO3, by adding the atomic masses of all atoms in the formula: 2 N, 8 H, 1 C, and 3 O.
(b) Divide the given mass of ammonium carbonate (6.955 g) by its molar mass to find the number of moles of (NH4)2CO3.
(b) Multiply the number of moles of (NH4)2CO3 by 2 to find the number of moles of ammonium ions, since each formula unit contains 2 NH4+ ions.

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Key Concepts

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

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in a molecule. For example, the molar mass of iron(III) sulfate (Fe2(SO4)3) can be determined by adding the masses of iron, sulfur, and oxygen in the compound.
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Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows us to convert between moles of different substances using balanced chemical equations. In the context of the question, stoichiometry helps in determining the number of moles of ammonium ions from the mass of ammonium carbonate.
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Avogadro's Number

Avogadro's number, approximately 6.022 x 10^23, is the number of particles (atoms, molecules, or ions) in one mole of a substance. This constant is essential for converting between the number of molecules and moles. For instance, to find the mass of 1.50 x 10^21 molecules of aspirin, one would first convert the number of molecules to moles using Avogadro's number.
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