Questions and Answers
Explain the concept of mole ratio as used in reaction stoichiometry problems. What is the source of this ratio?
Mole ratio is used as conversion factors from moles of a reactant to another. The ratio is also used to show the balanced equation of the reaction occurring.
What is molar mass?
The mass in grams of one mole of a substance.
What is the role of molar mass in reaction stoichiometry?
It is used as a conversion factor when the mass of a given substance is divided by its amount of substance.
Distinguish between ideal and real stoichiometric calculations.
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Distinguish between the limiting reactant and the excess reactant in a chemical reaction.
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Distinguish between the theoretical yield and actual yield in stoichiometric calculations.
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How does the value of the theoretical yield generally compare with the value of the actual yield?
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What is the percentage yield of a reaction?
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Why are actual yields usually less than calculated theoretical yields?
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Explain the stoichiometry of blowing air on a smoldering fire to keep the coals burning.
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Reaction stoichiometry involves the ____ between reactants and products in a chemical reaction.
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Relating one substance to another requires expressing the amount of each substance in ____.
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A ____ is the conversion factor that relates the amount in moles of any two substances in a chemical reaction.
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The mole ratio is derived from...
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Amount of substance is expressed in ____.
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Mass of a substance is expressed by using mass units such as ____, ____, or ____.
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Mass and amount of substance are _____ whereas moles and grams are _____
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A _____ is necessary to solve any stoichiometric problem.
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In an ideal stoichiometric calculation, the mass or the amount of any reactant or product can be calculated if...
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In actual reactions, the reactants may be present in proportions that differ from stoichiometric proportions required for a complete reaction in which all of each reactant is converted to product. This produces a ____.
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The _____ controls the maximum possible amount of product formed.
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For many reactions, the quantity of a product is ____ than the theoretical maximum for that product.
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____ shows the relationship between the theoretical yield and the actual yield for the product of a reaction.
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Study Notes
Mole Ratio and Molar Mass
- Mole ratio serves as a conversion factor from one reactant to another, reflecting the balanced equation of a chemical reaction.
- Molar mass is defined as the mass in grams of one mole of a substance and is crucial in stoichiometric calculations.
Role of Molar Mass in Stoichiometry
- Molar mass acts as a conversion factor when determining the relationship between mass and moles of a substance.
Ideal vs. Real Stoichiometric Calculations
- Ideal calculations predict the maximum amount of products possible under perfect conditions.
- Real calculations consider the actual yield that can be attained during a reaction.
Limiting and Excess Reactants
- The limiting reactant dictates the maximum amount of product that can be formed in a chemical reaction.
- The excess reactant is the substance that remains unconsumed after the reaction.
Theoretical Yield vs. Actual Yield
- Theoretical yield represents the maximum possible product obtainable, while actual yield refers to the amount actually produced during the reaction.
- Generally, theoretical yield exceeds actual yield.
Percentage Yield
- Percentage yield is calculated as the ratio of actual yield to theoretical yield, multiplied by 100.
Reasons for Lower Actual Yields
- Common factors for actual yields falling short of theoretical yield include incomplete reactions, impurities in reactants, competing side reactions, and loss of products during purification.
Stoichiometric Concepts in Reactions
- Stoichiometry deals with mass relationships between reactants and products.
- Relating substances requires expressing their amounts in moles.
Conversion Factors and Relationships
- The mole ratio is derived from the balanced chemical equation and serves as the conversion factor connecting moles of two substances.
- Balanced chemical equations are essential for solving stoichiometric problems and calculating mass or amount of reactants and products.
Practical Implications of Stoichiometry
- In real reactions, reactants may not be present in stoichiometric proportions, leading to limiting and excess reactant situations.
- The limiting reactant ultimately controls the maximum potential yield of products.
Summary of Yields
- In many cases, the quantity of product produced is inferior to the theoretical maximum.
- Percentage yield reflects the efficiency of a reaction by showing the relationship between theoretical and actual yields.
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Description
Test your understanding of stoichiometry with this review of Chapter 9. This quiz covers concepts like mole ratios and molar mass, crucial for solving reaction problems. Use these flashcards to reinforce your knowledge and prepare for your examinations.