Bond Enthalpy
Chemistry ⇒ Thermochemistry and Energetics
Bond Enthalpy starts at 11 and continues till grade 12.
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Arrange the following bonds in order of increasing bond enthalpy: C–C, C=C, C≡C.
Calculate the enthalpy change for the reaction:
CH4(g) + Cl2(g) → CH3Cl(g) + HCl(g)
Given: Bond enthalpies (kJ mol–1): C–H = 413, Cl–Cl = 243, C–Cl = 328, H–Cl = 431.
Calculate the enthalpy change for the reaction:
H2(g) + Cl2(g) → 2HCl(g)
Given: Bond enthalpies (kJ mol–1): H–H = 436, Cl–Cl = 243, H–Cl = 431.
Define bond enthalpy.
Describe how resonance affects bond enthalpy values.
Describe the relationship between bond length and bond enthalpy.
Explain why bond enthalpy values are not always exact for a given bond in different molecules.
Explain why the bond enthalpy of a bond in a polyatomic molecule may differ from that in a diatomic molecule.
Explain why the bond enthalpy of a C–H bond is higher than that of a C–C bond.
Explain why the bond enthalpy of F–F is lower than expected, despite fluorine being a small atom.
Explain why the bond enthalpy of O=O is less than that of N≡N.
Explain why the enthalpy change calculated using bond enthalpies may differ from the actual enthalpy change measured experimentally.
Given the following bond enthalpies: H–H = 436 kJ mol–1, O=O = 498 kJ mol–1, O–H = 463 kJ mol–1. Calculate the enthalpy change for the reaction:
2H2(g) + O2(g) → 2H2O(g)
Given the following bond enthalpies: N≡N = 945 kJ mol–1, H–H = 436 kJ mol–1, N–H = 391 kJ mol–1. Calculate the enthalpy change for the reaction:
N2(g) + 3H2(g) → 2NH3(g)
State one reason why bond enthalpy values are important in thermochemistry.
State the formula for calculating the enthalpy change of a reaction using bond enthalpies.
The average bond enthalpy of a C–H bond in methane is 413 kJ mol–1. How much energy is required to break all four C–H bonds in one mole of methane?
The bond enthalpy of a C–N bond is 305 kJ mol–1. How much energy is required to break 2 moles of C–N bonds?
The bond enthalpy of H–Cl is 431 kJ mol–1. How much energy is released when one mole of HCl is formed from its elements in the gas phase?
The bond enthalpy of O–H is 463 kJ mol–1. How much energy is required to break all O–H bonds in 2 moles of H2O?
