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Ch.5 Classification & Balancing of Chemical Reactions
McMurry - Fundamentals of General, Organic, and Biological Chemistry 8th Edition
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
All textbooksMcMurry 8th EditionCh.5 Classification & Balancing of Chemical ReactionsProblem 17
Chapter 5, Problem 17

Reaction of A (green spheres) with B (blue spheres) is shown in the following diagram:

Which equation best describes the reaction?
a. A2 + 2 B → A2B2
b. 10 A + 5 B2 → 5 A2B2
c. 2 A + B2 → A2B2
d. 5 A + 5 B2 → 5 A2B2

Verified step by step guidance
1
Step 1: Analyze the diagram. In the left box, observe that the red spheres (A) are paired as A₂ molecules, and the purple spheres (B) are paired as B₂ molecules. In the right box, observe that each A₂ molecule has combined with a B₂ molecule to form A₂B₂ molecules.
Step 2: Count the number of molecules in the left box. There are 5 A₂ molecules and 5 B₂ molecules. This indicates a 1:1 ratio of A₂ to B₂ molecules.
Step 3: Count the number of molecules in the right box. There are 5 A₂B₂ molecules formed, which matches the number of reactants in the left box.
Step 4: Write the balanced chemical equation based on the observations. Since 5 A₂ molecules react with 5 B₂ molecules to form 5 A₂B₂ molecules, the equation is: 5 A₂ + 5 B₂ → 5 A₂B₂.
Step 5: Compare the balanced equation to the given options. The correct answer is d. 5 A + 5 B₂ → 5 A₂B₂.

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Key Concepts

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

Chemical Reaction

A chemical reaction involves the transformation of reactants into products through the breaking and forming of chemical bonds. In this context, the green spheres (A) and blue spheres (B) represent different chemical species that interact to form a new compound. Understanding the nature of these interactions is crucial for determining the correct chemical equation that describes the reaction.
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Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the conservation of mass. It allows chemists to predict the quantities of substances consumed and produced in a reaction. In this question, stoichiometric coefficients in the proposed equations indicate the ratio of A and B that react to form the product, A₂B₂.
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Molecular Representation

Molecular representation visually depicts the arrangement and interaction of atoms in a chemical reaction. The diagram shows how green and blue spheres (representing different atoms or molecules) rearrange during the reaction. Analyzing these representations helps in understanding the formation of products and is essential for selecting the correct chemical equation that accurately reflects the reaction process.
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Related Practice
Textbook Question

Why is it not possible to balance an equation by changing the subscript on a substance, say from H2O to H2O2?

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Textbook Question

What is meant by the term 'balanced equation'?

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Textbook Question

Potassium, a silvery metal, reacts with bromine, a corrosive, reddish liquid, to yield potassium bromide, a white solid. Write the balanced equation, and identify the oxidizing and reducing agents.

Textbook Question

Identify the oxidized reactant, the reduced reactant, the oxidizing agent, and the reducing agent in the following reactions:

a. Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)

b. Mg(s) + Cl2(g) → MgCl2(s)

c. 2 Al(s) + Cr2O3(s) → 2 Cr(s) + Al2O3(s)

Textbook Question

Assume that the mixture of substances in drawing (a) undergoes a reaction. Which of the drawings (b)–(d) represent a product mixture consistent with the law of conservation of mass?

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Textbook Question

An aqueous solution of a cation (represented as blue spheres in the diagram) is allowed to mix with a solution of an anion (represented as green spheres) and the following result is obtained:

Which combinations of cation and anion, chosen from the following lists, are compatible with the observed results? Explain.

Cations: Na+, Ca2+, Ag+, Ni2+

Anions: Cl−, CO23–, CrO42–, NO3–