Question

Calculate the enthalpy change of the isomerization of but-2-ene to 2-methylpropene given the standard enthalpy of formation of but-2-ene is -20.4 kJ/mol and that of 2-methylpropene is -27.0 kJ/mol. The reaction is carried out at constant pressure and 298 K.

Answer 1

To calculate the enthalpy change  H  of the isomerization reaction, we can use the following formula:H =  Hf products  -  Hf reactants In this case, the reaction is:but-2-ene  2-methylpropeneThe standard enthalpy of formation  Hf  of but-2-ene is -20.4 kJ/mol, and that of 2-methylpropene is -27.0 kJ/mol.Using the formula, we can calculate the enthalpy change for the reaction:H =  -27.0 kJ/mol  -  -20.4 kJ/mol H = -27.0 + 20.4H = -6.6 kJ/molThe enthalpy change for the isomerization of but-2-ene to 2-methylpropene is -6.6 kJ/mol.