Question

the enthalpy change for the following reaction is 95.4 kj. using bond energies, estimate the n-h bond energy in n2h4(g). n2(g) 2h2(g)n2h4(g)

Answer 1

To estimate the N-H bond energy in N2H4(g), we can use bond energies. The bond energy of N-H can be calculated by subtracting the energy required to break the N-H bonds from the energy required to form the H-H bonds.

Step-by-step explanation:

The enthalpy change for the reaction provided is 95.4 kJ. To estimate the N-H bond energy in N2H4(g), we can use bond energies. We need to consider the bonds being broken and the bonds being formed in the reaction. In the reactant side, we have two N-H bonds being broken and four N-N bonds being broken. In the product side, we have four N=N bonds being formed and eight H-H bonds being formed. The bond energy of N-N is 163 kJ/mol, so the energy required to break four N-N bonds is 4 * 163 kJ/mol = 652 kJ/mol. The bond energy of H-H is 436 kJ/mol, so the energy required to form eight H-H bonds is 8 * 436 kJ/mol = 3488 kJ/mol. Now we need to subtract the energy required to break the N-H bonds from the energy required to form the H-H bonds. The total bond energy required to break the N-H bonds is 652 kJ/mol, so the N-H bond energy is 652 kJ/mol / 2 = 326 kJ/mol.

Answer 2

To estimate the N-H bond energy in N2H4(g) using bond energies, calculate the total bond energy of the reactants and compare it to the total bond energy of the products. Based on the given reaction, the N-H bond energy in N2H4(g) is estimated to be approximately 863.3 kJ/mol.

Step-by-step explanation:

To estimate the N-H bond energy in N2H4(g) using bond energies, we need to calculate the total bond energy of the reactants and compare it to the total bond energy of the products. Based on the given reaction:

N2(g) + 2H2(g) → N2H4(g)

We can look up the bond energies for each bond in Table 9.4 and calculate the total bond energy for the reactants and products:

• Total bond energy of reactants: 1(N≡N) + 2(H-H) = 1(945 kJ/mol) + 2(436 kJ/mol) = 1817 kJ/mol
• Total bond energy of products: 2(N-H) = 2(x kJ/mol)

Since the enthalpy change for the reaction is given as 95.4 kJ, we can set up the equation:

Total bond energy of reactants - Total bond energy of products = Enthalpy change

1817 kJ/mol - 2x kJ/mol = 95.4 kJ/mol

Solving for x, we can estimate the N-H bond energy in N2H4(g) to be x = 863.3 kJ/mol.