Textbook Question
A common form of elemental phosphorus is the tetrahedral P4 molecule, where all four phosphorus atoms are equivalent:
(b) How many P-P bonds are there in the molecule?
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Ch.8 - Basic Concepts of Chemical Bonding
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement140
- Ch.2 - Atoms, Molecules, and Ions192
- Ch.3 - Chemical Reactions and Reaction Stoichiometry172
- Ch.4 - Reactions in Aqueous Solution156
- Ch.5 - Thermochemistry151
- Ch.6 - Electronic Structure of Atoms137
- Ch.7 - Periodic Properties of the Elements127
- Ch.8 - Basic Concepts of Chemical Bonding143
- Ch.9 - Molecular Geometry and Bonding Theories167
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces97
- Ch.12 - Solids and Modern Materials129
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics175
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Acid-Base Equilibria127
- Ch.17 - Additional Aspects of Aqueous Equilibria133
- Ch.18 - Chemistry of the Environment88
- Ch.19 - Chemical Thermodynamics140
- Ch.20 - Electrochemistry137
- Ch.21 - Nuclear Chemistry99
- Ch.22 - Chemistry of the Nonmetals66
- Ch.23 - Transition Metals and Coordination Chemistry69
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry11
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 8, Problem 105b
Acetylene (C2H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their chemical properties. (b) By referring to Appendix C, look up the enthalpies of formation of acetylene and nitrogen. Which compound is more stable?
Verified step by step guidance1
Identify the enthalpy of formation (\( \Delta H_f^\circ \)) for each compound from Appendix C.
Recall that the enthalpy of formation is the change in enthalpy when one mole of a compound is formed from its elements in their standard states.
Understand that a more negative enthalpy of formation indicates a more stable compound, as it releases more energy upon formation.
Compare the \( \Delta H_f^\circ \) values of acetylene (C_2H_2) and nitrogen (N_2).
Determine which compound has a more negative \( \Delta H_f^\circ \) value to conclude which is more stable.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Enthalpy of Formation
Enthalpy of formation is the change in enthalpy when one mole of a compound is formed from its elements in their standard states. It provides insight into the stability of a compound; lower enthalpy values indicate greater stability. For example, if acetylene has a higher enthalpy of formation than nitrogen, it suggests that nitrogen is more stable under standard conditions.
Triple Bonds
A triple bond consists of one sigma bond and two pi bonds, resulting in a strong interaction between two atoms. In acetylene (C2H2), the carbon atoms are connected by a triple bond, which contributes to its reactivity and energy content. In contrast, nitrogen (N2) also has a triple bond, but its stability is enhanced by the strong bond energy, making it less reactive than acetylene.
Chemical Stability
Chemical stability refers to the tendency of a compound to maintain its structure and resist change under various conditions. Factors influencing stability include bond strength, molecular structure, and enthalpy of formation. In this context, comparing the enthalpies of formation of acetylene and nitrogen helps determine which compound is more stable, with lower energy compounds being more stable.
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Related Practice
Textbook Question
Acetylene (C2H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their chemical properties. (c) Write balanced chemical equations for the complete oxidation of N2 to form N2O5(g) and of acetylene to form CO2(g) and H2O(g). Write a balanced chemical equation for the complete oxidation of acetylene to form CO2(g) and H2O(g).
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Textbook Question
Acetylene (C2H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their chemical properties. (e) Both N2 and C2H2 possess triple bonds with quite high bond enthalpies (Table 8.3). Calculate the enthalpy of hydrogenation per mole for both compounds: acetylene plus H2 to make methane, CH4; nitrogen plus H2 to make ammonia, NH3.
Textbook Question
One scale for electronegativity is based on the concept that the electronegativity of any atom is proportional to the ionization energy of the atom minus its electron affinity: electronegativity = k1I - EA2, where k is a proportionality constant. (b) Why are both ionization energy and electron affinity relevant to the notion of electronegativity?
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