Textbook Question
Based on bond energies, which atmospheric gas in each pair do you think is more stable? Explain.
a. O2 or N2
b. CO or CO2
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Ch.7 Chemical Reactions: Energy, Rate and Equilibrium
McMurry8th EditionFundamentals of GOBISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
Chapter 7, Problem 4c
The following equation shows the conversion of aluminum oxide (from the ore bauxite) to aluminum:
2 Al2O3(s) → 4 Al(s) + 3 O2(g) ∆H = +801 kcal/mol (+3350 kJ/mol)
c. How many kilocalories are required to produce 10.0 g of aluminum? How many kilojoules?
Verified step by step guidance1
Step 1: Calculate the molar mass of aluminum (Al) using the periodic table. The atomic mass of aluminum is approximately 26.98 g/mol.
Step 2: Convert the given mass of aluminum (10.0 g) to moles using the formula: moles = mass / molar mass. Substitute the values: moles = 10.0 g / 26.98 g/mol.
Step 3: Use the stoichiometry of the reaction to determine the relationship between moles of aluminum and the enthalpy change (∆H). From the balanced equation, 4 moles of Al correspond to +801 kcal. Set up a proportion to find the energy required for the calculated moles of aluminum.
Step 4: Convert the energy from kilocalories to kilojoules using the conversion factor: 1 kcal = 4.184 kJ. Multiply the energy in kilocalories by 4.184 to find the energy in kilojoules.
Step 5: Report the energy required in both kilocalories and kilojoules, ensuring the units are clearly labeled.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
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 calculate the amounts of substances consumed and produced in a reaction based on balanced chemical equations. In this case, stoichiometry will help determine how much aluminum can be produced from a given mass of aluminum oxide.
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Stoichiometry
Molar Mass
Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between the mass of a substance and the number of moles, which is necessary for stoichiometric calculations. For aluminum, the molar mass is approximately 27 g/mol, which will be used to find out how many moles correspond to 10.0 g of aluminum.
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Enthalpy Change (∆H)
Enthalpy change (∆H) represents the heat absorbed or released during a chemical reaction at constant pressure. In this equation, the positive value indicates that the reaction is endothermic, meaning it requires energy input. Understanding ∆H is crucial for calculating the total energy required to produce a specific amount of aluminum from aluminum oxide, as it directly relates to the amount of heat needed per mole of aluminum produced.
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Related Practice
Textbook Question
In photosynthesis, green plants convert carbon dioxide and water into glucose (C6H12O6) according to the following equation:
6 CO2(g) + 6 H2O(l) → C6H12O6(aq) + 6 O2(g)
a. Estimate ∆H for the reaction using bond dissociation energies from Table 7.1. Give your answer in kcal/mol and kJ/mol. (C6H12O6 has five C―C bonds, seven C―H bonds, seven C―O bonds, and five O―H bonds).
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Textbook Question
In photosynthesis, green plants convert carbon dioxide and water into glucose (C6H12O6) according to the following equation:
6 CO2(g) + 6 H2O(l) → C6H12O6(aq) + 6 O2(g)
b. Is the reaction endothermic or exothermic?
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Textbook Question
Does entropy increase or decrease in the following processes?
a. Polymeric complex carbohydrates are metabolized by the body, converted into smaller simple sugars.
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Textbook Question
Does entropy increase or decrease in the following processes?
c. 2 SO2(g) + O2(g) → 2 SO3(g)
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Textbook Question
Do the following reactions favor reactants or products at equilibrium? Give relative concentrations at equilibrium.
a. Sucrose(aq) + H2O(l) ⇌ Glucose(aq) + Fructose(aq) K = 1.4 × 105
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