Use bond energies to estimate the enthalpy change for the following reaction
C2H2 + H2-> C2H4
i figured the bonds broken are:
1 C triple bond C 1(812kj/mol)
2 C-H 2(414kj/mol)
1 H-H 1(435kj/mol)
Bonds formed
1 C=C 1(590kj/mol)
4 C-H 4(435kj/mol)
Is this right
Yes, your analysis of the bonds broken and formed in the reaction is correct.
Bonds broken:
1 C triple bond C: 1(812 kJ/mol)
2 C-H: 2(414 kJ/mol)
1 H-H: 1(435 kJ/mol)
Bonds formed:
1 C=C: 1(590 kJ/mol)
4 C-H: 4(435 kJ/mol)
To estimate the enthalpy change (ΔH) for the reaction, you need to calculate the total energy change for the bonds broken and the total energy change for the bonds formed, and then take the difference.
Energy change for bonds broken:
1(812 kJ/mol) + 2(414 kJ/mol) + 1(435 kJ/mol)
Energy change for bonds formed:
1(590 kJ/mol) + 4(435 kJ/mol)
Finally, subtract the energy change for bonds formed from the energy change for bonds broken to obtain the estimated enthalpy change for the reaction.
Yes, your assessment of the bonds broken and formed in the reaction is correct. To estimate the enthalpy change (ΔH) for the reaction using bond energies, you can follow these steps:
1. Determine the total energy required to break the bonds in the reactants:
- For C2H2:
- Breaking 1 C≡C bond requires 812 kJ/mol.
- Breaking 2 C-H bonds requires 2 × 414 kJ/mol.
- For H2:
- Breaking 1 H-H bond requires 435 kJ/mol.
So the total energy required to break the bonds in the reactants is:
1 × 812 kJ/mol + 2 × 414 kJ/mol + 1 × 435 kJ/mol = __________ kJ/mol
2. Determine the total energy released when the new bonds form in the products:
- For C2H4:
- Forming 1 C=C bond releases 590 kJ/mol.
- Forming 4 C-H bonds releases 4 × 435 kJ/mol.
So the total energy released when the new bonds form in the products is:
1 × 590 kJ/mol + 4 × 435 kJ/mol = __________ kJ/mol
3. Calculate the overall energy change by subtracting the energy required to break the bonds from the energy released when the new bonds form:
ΔH = (Energy released in bonds formed) - (Energy required in bonds broken)
ΔH = (__________ kJ/mol) - (__________ kJ/mol)
ΔH = __________ kJ/mol
By substituting the correct values determined in Steps 1 and 2, you can find the estimated enthalpy change (ΔH) for the given reaction.