Concept explainers
Interpretation:
The maximum
Concept Introduction:
Bond Enthalpy:
The measure of stability of molecule is bond enthalpy. The change in enthalpy is related in breaking a specific bond of 1 mole of gaseous molecule. In solids and liquids bond enthalpies are affected by neighboring molecules. There is possibility to predict the enthalpy of reaction using the average bond enthalpies. Energy is always needed for the breaking of
The enthalpy of reaction in gas phase is given by,
Where,
BE= Bond enthalpy and
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CHEMISTRY:ATOMS FIRST (LL)>CUSTOM PKG.<
- Bond Enthalpy When atoms of the hypothetical element X are placed together, they rapidly undergo reaction to form the X2 molecule: X(g)+X(g)X2(g) a Would you predict that this reaction is exothermic or endothermic? Explain. b Is the bond enthalpy of X2 a positive or a negative quantity? Why? c Suppose H for the reaction is 500 kJ/mol. Estimate the bond enthalpy of the X2 molecule. d Another hypothetical molecular compound, Y2(g), has a bond enthalpy of 750 kJ/mol, and the molecular compound XY(g) has a bond enthalpy of 1500 kJ/mol. Using bond enthalpy information, calculate H for the following reaction. X2(g)+Y2(g)2XY(g) e Given the following information, as well as the information previously presented, predict whether or not the hypothetical ionic compound AX is likely to form. In this compound, A forms the A+ cation, and X forms the X anion. Be sure to justify your answer. Reaction: A(g)+12X2(g)AX(s)The first ionization energy of A(g) is 400 kJ/mol. The electron affinity of X(g) is 525 kJ/mol. The lattice energy of AX(s) is 100 kJ/mol. f If you predicted that no ionic compound would form from the reaction in Part e, what minimum amount of AX(s) lattice energy might lead to compound formation?arrow_forwardUsing the bond energies provided, calculate the enthalpy of the reaction (∆Hrxn, in kJ) for the combustion of methanol shown below. CH3OH(l) +3/2 O2 (g) → CO2 (g) + 2 H2O(g)arrow_forwardThe average bond enthalpy for C−H is 413 kJ/mol. 413 kJ of energy is required to break a mole of CH into atoms: CH(g)→C(g)+H(g), ΔH=413 kJ Using this information, and your answer from Part A, calculate the enthalpy change of the reaction from Part B. That is, calculate the energy required to break only the carbon-carbon bonds in benzene. PART A ANSWER ΔH∘rxn = 5535.1 kJ.. PART B ANSWER C6H6(g)→6CH(g)arrow_forward
- Calculate the Enthalpy Change (ΔH) from average bond energies, which have been listed below in KJ/mol, for the following reaction and identify the nature of the reaction: CH3COOH + CH3OH → CH3COOCH3 + H2O [C‒H: 413; C‒C: 347; C=O: 745; C=C: 614; Cl‒Cl: 239, C‒O: 358; O‒H: 467]arrow_forwardWith reference to the “Chemistry Put to Work” box on explosives, (a) use bond enthalpies to estimate the enthalpy change for the explosion of 1.00 g of nitroglycerin. (b) Write a balanced equation for the decomposition of TNT. Assume that, upon explosion, TNT decomposes into N2(g), CO2(g), H2O(g), and C(s).arrow_forward(a) Compare the bond enthalpies (Table 8.3) of the carbon–carbon single, double, and triple bonds to deduce an averageπ -bond contribution to the enthalpy. What fraction ofa single bond does this quantity represent? (b) Make a similarcomparison of nitrogen–nitrogen bonds. What do youobserve? (c) Write Lewis structures of N2H4, N2H2, and N2,and determine the hybridization around nitrogen in eachcase. (d) Propose a reason for the large difference in yourobservations of parts (a) and (b).arrow_forward
- Many free radicals combine to form molecules that do not contain any unpaired electrons. The driving force for the radical-radical combination reaction is the formation of a new electron-pair bond. Consider the chemical equation. N(g)+NO(g) NNO(g) Write Lewis formulas for the reactant and product species in the chemical equation. Include nonbonding electrons.arrow_forwardHydrazine, N2H4, burns in oxygen as follows: N2H4 + O2 → N2 + 2H2O [The bond energies in kJ/mol are: N-H = 388; N-N 163; N≡N 944; O-H 463; O=O 496] Draw the chemical structures of the reactants and products and give the formula to calculate enthalpy change in a reaction, ΔH.arrow_forwardUsing the table of average bond dissociation enthalpies at 25°C, determine which of the following reactions are energetically favorable at room temperature. Assume that ▲S = 0.arrow_forward
- 5. Consider the reaction between hydrazine and hydrogen to produce ammonia, N2H4(g)+H2(g)→2NH3(g)N2H4(g)+H2(g)→2NH3(g). Use enthalpies of formation and bond enthalpies to estimate the enthalpy of the nitrogen-nitrogen bond in N2H4N2H4. (Hint: In an N2H4N2H4 molecule, each NN atom has single bonds to the adjacent NN atom and two HH atoms. In an NH3NH3 molecule, the central NN atom has single bonds to three HH atoms.)arrow_forwardThe two compounds nitrogen dioxide and dinitrogen tetraoxide are introduced in Section 3.13. (a) NO2 is an odd-electron compound. Draw the best Lewis diagrams possible for it, recognizing that one atom cannot achieve an octet configuration. Use formal charges to decide whether that should be the (central) nitrogen atom or one of the oxygen atoms. (b) Draw resonance forms for N2O4 that obey the octet rule. The two N atoms are bonded in this molecule.arrow_forwardCalculate the enthalpy change from bond energies for each of these reactions: 1. Н-(g) + F:(g) — 2 HF(g) AH= 2. CH(g) + 20-(g) — СО2(g) + 2H-0 (g) AH= 3. CO(g) + 2H2(g) → CH;OH(I) AH= 4. 2H2(g) + Oz(g) – 2H;O(g) AH= 5. 2H2O(g) → 2H2(g) + O2(g) AH= 6. H2CCH2(g) + Cl2(g) → CIH2CCH2CI(g) AH=arrow_forward
- Chemistry: The Molecular ScienceChemistryISBN:9781285199047Author:John W. Moore, Conrad L. StanitskiPublisher:Cengage LearningGeneral Chemistry - Standalone book (MindTap Cour...ChemistryISBN:9781305580343Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; DarrellPublisher:Cengage Learning