Concept explainers
Interpretation: The value of
Concept Introduction:
A chemical compound can be formed by either ionic bond or covalent bond between bonded atoms. The ionic compound is formed by opposite charge ions; cations and anions. The covalent compound is formed by sharing of electrons between bonded atoms.
The bond energy of a chemical bond can be defined as the energy required to break that chemical bond. The bond energy that is needed to break the bonds in reactant molecule and the energy released to form
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Chapter 13 Solutions
Chemical Principles
- 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_forwardThe standard enthalpies of formation for S(g), F(g), SF4(g), and SF6(g) are +278.8, +79.0, 775, and +1209 KJ/mol, respectively. a. Use these data to estimate the energy of an SF bond. b. Compare your calculated value to the value given in Table 3-3. What conclusions can you draw? c. Why are the Hf values for S(g) and F(g) not equal to zero, since sulfur and fluorine are elements?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_forward
- Explain the decomposition of nitroglycerin in terms of relative bond enthalpies.arrow_forwardCalculate the enthalpy of reaction for HCN(g)H(g)+C(g)+N(g) from enthalpies of formation (see Appendix C). Given that the CH bond enthalpy is 411 kJ/mol, obtain a value for the CN bond enthalpy. Compare your result with the value given in Table 9.5.arrow_forwardhat is the enthalpy change for a process? Is enthalpy a state function? In what experimental apparatus are enthalpy changes measured?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_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_forwardGiven the following data: NO2(g) NO(g) + O(g)H = 233 kJ 2O3(g) 3O2(g)H = 427 kJ NO(g) + O3(g) NO2(g) + O2(g)H = 199 kJ Calculate the bond energy for the O2 bond, that is, calculate H for: O2(g) 2O(g)H = ?arrow_forward
- A 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_forwardWhen a reaction is exothermic, is the sum of bond energies of products or of reactants greater?arrow_forwardWhich statement(s) is/are true about bond enthalpy? (a) The bond energy for a triple bond between A and B is three times that of a single bond between A and B. (b) H for the breaking of a bond is always a negative number. (c) Energy is required to make a bond. (d) Bond enthalpy is defined only for bonds broken or formed in the gaseous state. (e) The presence of bonds does not influence the geometry of a molecule. However, the presence of bonds affects the value of the bond enthalpy between two atoms.arrow_forward
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