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Problem: The average C—H bond energy in CH4 is 415 kJ/mol. Use following table and the following data to calculate the average C—H bond energy in ethane (C2H6; C—C bond), in ethene (C2H4; C=C bond), and in ethyne (C 2H2; C≡C bond):C2H6(g) + H2(g) ⟶ 2CH4(g)               ΔH°rxn =    −65.07 kJ/molC2H4(g) + 2H2(g) ⟶ 2CH4(g)             ΔH°rxn = − 202.21 kJ/molC2H2(g) + 3H2(g) ⟶ 2CH4(g)             ΔH°rxn =   −376.74 kJ/mol

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FREE Expert Solution

We’re being asked to calculate the calculate the average C—H bond energy in ethane (C2H6; C—C bond), in ethene (C2H4; C=C bond), and in ethyne (C 2H2; C≡C bond).


To calculate the ΔH°rxn using bond energies, we’re going to use the following equation:

H°rxn=Hbond reactants-Hbond products


Let’s first figure out what kind of bonds and how many moles are present in each reactants and products because the given bond energies are per mole.

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Problem Details

The average C—H bond energy in CH4 is 415 kJ/mol. Use following table and the following data to calculate the average C—H bond energy in ethane (C2H6; C—C bond), in ethene (C2H4; C=C bond), and in ethyne (C 2H2; C≡C bond):


C2H6(g) + H2(g) ⟶ 2CH4(g)               ΔH°rxn =    −65.07 kJ/mol
C2H4(g) + 2H2(g) ⟶ 2CH4(g)             ΔH°rxn = − 202.21 kJ/mol
C2H2(g) + 3H2(g) ⟶ 2CH4(g)             ΔH°rxn =   −376.74 kJ/mol

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Bond Energy concept. If you need more Bond Energy practice, you can also practice Bond Energy practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Davis' class at UCF.

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition. You can also practice Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition practice problems.