To calculate the enthalpy of isomerization for the reaction of cis-2-butene to trans-2-butene, we can use Hess's Law. Hess's Law states that the enthalpy change of a reaction is the same whether it occurs in one step or several steps. In this case, we can use the heat of combustion values provided to calculate the enthalpy change for the isomerization reaction.First, let's write the combustion reactions for cis-2-butene, trans-2-butene, and butane:1. cis-2-butene + O CO + HO H = -3338.9 kJ/mol 2. trans-2-butene + O CO + HO H = -3478.6 kJ/mol 3. butane + O CO + HO H = -2877.2 kJ/mol Now, we want to manipulate these reactions to obtain the isomerization reaction:cis-2-butene trans-2-buteneTo do this, we can reverse reaction 1 and add it to reaction 2:1. CO + HO cis-2-butene + O H = +3338.9 kJ/mol 2. trans-2-butene + O CO + HO H = -3478.6 kJ/mol Adding these two reactions, we get:cis-2-butene trans-2-butene H = -3478.6 + 3338.9 Now, we can calculate the enthalpy change for the isomerization reaction:H = -3478.6 kJ/mol + 3338.9 kJ/mol = -139.7 kJ/molTherefore, the enthalpy of isomerization for the reaction of cis-2-butene to its trans counterpart is -139.7 kJ/mol.