Concept explainers
Interpretation:
The
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,
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General Chemistry - Standalone book (MindTap Course List)
- The equation for the combustion of gaseous methanol is 2 CH3OH(g) + 3 O2(g) 2 CO2(g) + 4 H2O(g) (a) Using the bond dissociation enthalpies in Table 8.8, estimate the enthalpy change for this reaction. What is the enthalpy of combustion of one mole of gaseous methanol? (b) Compare your answer in part (a) with the value of tHcalculated using enthalpies of formation data.arrow_forwardGiven the following data calculate H for the reaction On the basis of the enthalpy change, is this a useful reaction for the synthesis of ammonia?arrow_forwardBond 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_forward
- Using the standard enthalpy of formation data in Appendix G, calculate the bond energy of the carbon-sulfur double bond in CS2.arrow_forwardWrite all resonance structures of chlorobenzene, C6H5Cl, a molecule with the same cyclic structure as benzene. In all structures, keep the CCl bond as a single bond. Which resonance structures are the most important?arrow_forwardA commercial process for preparing ethanol (ethyl alcohol), C2H5OH, consists of passing ethylene gas. C2H4, and steam over an acid catalyst (to speed up the reaction). The gas-phase reaction is Use bond enthalpies (Table 9.5) to estimate the enthalpy change for this reaction when 37.0 g of ethyl alcohol is produced.arrow_forward
- Using the bond dissociation enthalpies in Table 8.8, estimate the enthalpy of combustion of gaseous methane, CH4, to give water vapor and carbon dioxide gas.arrow_forwardEstimate H for the following reactions using bond energies given in Table 8.5. 3CH2=CH2(g) + 3H2(g) 3CH2CH3(g) The enthalpies of formation for C6H6(g) and C6H12 (g) are 82.9 and 90.3 kJ/mol. respectively. Calculate H for the two reactions using standard enthalpies of formation from Appendix 4. Account for any differences between the results obtained from the two methods.arrow_forwardExplain the decomposition of nitroglycerin in terms of relative bond enthalpies.arrow_forward
- Compare your answers from parts a and b of Exercise 69 of Chapter 3 with H values calculated for each reaction using standard enthalpies of formation in Appendix 4. Do enthalpy changes calculated from bond energies give a reasonable estimate of the actual values?arrow_forwardFor the reactions of molecular hydrogen with fluorine and with chlorine: (a) Calculate the enthalpy change for breaking all the bonds in the reactants. (b) Calculate the enthalpy change for forming all the bonds in the products. (c) From the results in parts (a) and (b), calculate the enthalpy change for the reaction. (d) Which reaction is most exothermic?arrow_forwardMethanol can be made by partial oxidation of methane using O2 in the presence of a catalyst: 2 CH4(g) + O2(g) 2 CH3OH() Use bond dissociation enthalpies to estimate the enthalpy change for this reaction. Compare the value obtained to the value calculated using standard enthalpies of formation.arrow_forward
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