Textbook Question
The combustion of one mole of liquid octane, CH3(CH2)6CH3, produces 5470 kJ of heat. Calculate how much heat is produced if 1.000 gallon of octane is combusted.
Ch.3 - Chemical Reactions and Reaction Stoichiometry
Chapter 3, Problem 73b
(b) Why are the amounts of products formed in a reaction determined only by the amount of the limiting reactant?
Verified step by step guidance1
Identify the concept of a limiting reactant: In a chemical reaction, the limiting reactant is the substance that is completely consumed first, stopping the reaction from continuing because there is no more of this reactant to react with the other reactants.
Understand the stoichiometry of the reaction: The balanced chemical equation provides the mole ratio of reactants to products. This ratio is crucial in determining how much product can be formed from a given amount of reactant.
Determine the amount of product formed: Since the limiting reactant is completely used up, it dictates the maximum amount of product that can be formed. The other reactants may be in excess, but they cannot produce more product without the limiting reactant.
Calculate the theoretical yield: Using the stoichiometric coefficients from the balanced equation, calculate the amount of product that can be formed from the limiting reactant. This is known as the theoretical yield.
Recognize the practical implications: In practical terms, the limiting reactant determines the efficiency and cost-effectiveness of a reaction, as it limits the amount of product that can be obtained, regardless of the quantities of other reactants present.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Limiting Reactant
The limiting reactant is the substance in a chemical reaction that is completely consumed first, thus determining the maximum amount of product that can be formed. Once this reactant is used up, the reaction cannot proceed further, regardless of the amounts of other reactants present. Understanding which reactant is limiting is crucial for predicting the yield of products.
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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 involves using balanced chemical equations to calculate the amounts of substances consumed and produced. This concept is essential for determining how much product can be formed based on the amount of the limiting reactant.
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Reaction Completion
In a chemical reaction, completion refers to the point at which the reactants have been converted into products. The amount of product formed is directly related to the limiting reactant, as it dictates when the reaction stops. Understanding this concept helps clarify why the limiting reactant controls the overall yield of the reaction.
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Related Practice
Textbook Question
(a) Define the terms limiting reactant and excess reactant.
Textbook Question
(c) Why should you base your choice of which compound is the limiting reactant on its number of initial moles, not on its initial mass in grams?
Textbook Question
(a) Define the terms theoretical yield, actual yield, and percent yield.
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Textbook Question
(b) Why is the actual yield in a reaction almost always less than the theoretical yield?
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