Chemistry Practice Problems Bond Energy Practice Problems Solution: (a) The nitrogen atoms in an N2 molecule are held ...

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Solution: (a) The nitrogen atoms in an N2 molecule are held together by a triple bond; use enthalpies of formation in Appendix C to estimate the enthalpy of this bond, D(N≡N).(b) Consider the reaction between hydrazine and hydrogen to produce ammonia, N2H4(g) + H2(g) → 2NH3(g). Use enthalpies of formation and bond enthalpies to estimate the enthalpy of the nitrogen– nitrogen bond in N2H4. (c) Based on your answers to parts (a) and (b), would you predict that the nitrogen–nitrogen bond in hydrazine is weaker than, similar to, or stronger than the bond in N2?

Problem

(a) The nitrogen atoms in an N2 molecule are held together by a triple bond; use enthalpies of formation in Appendix C to estimate the enthalpy of this bond, D(N≡N).

(b) Consider the reaction between hydrazine and hydrogen to produce ammonia, N2H4(g) + H2(g) → 2NH3(g). Use enthalpies of formation and bond enthalpies to estimate the enthalpy of the nitrogen– nitrogen bond in N2H4

(c) Based on your answers to parts (a) and (b), would you predict that the nitrogen–nitrogen bond in hydrazine is weaker than, similar to, or stronger than the bond in N2?

Solution

We’re being asked to predict if the nitrogen–nitrogen bond in hydrazine is weaker than, similar to, or stronger than the bond in N2.

for this problem, we're going to use the following steps:

Step 1: Determine the enthalpy of the N≡N in N2.
Step 2: Calculate the ΔHrxn for the reaction between hydrazine and hydrogen to produce ammonia using enthalpies of formation.
Step 3: Calculate the nitrogen– nitrogen bond in N2H4 using bond energies.
Step 4: Determine if the nitrogen–nitrogen bond in hydrazine is weaker than, similar to, or stronger than the bond in N2.

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