Calculate the enthalpy change for the polymerization of 2-methyl-1,3-butadiene (MBC) if 1 mole of MBC is polymerized in a perfectly insulated container at a constant temperature of 25°C. The reaction equation for the polymerization of MBC is given as:nC5H8 (MBC) → (C5H8) (Polymer)Given the bond dissociation energies (in kJ/mol) for the following bonds:C-C bond = 348C-H bond = 413Assume that the enthalpy change of vaporization of MBC is negligible.

Question

Calculate the enthalpy change for the polymerization of 2-methyl-1,3-butadiene (MBC) if 1 mole of MBC is polymerized in a perfectly insulated container at a constant temperature of 25°C. The reaction equation for the polymerization of MBC is given as:nC5H8 (MBC)  →  (C5H8) (Polymer)Given the bond dissociation energies (in kJ/mol) for the following bonds:C-C bond = 348C-H bond = 413Assume th

Answer 1

To calculate the enthalpy change for the polymerization of 2-methyl-1,3-butadiene  MBC , we need to determine the number of bonds broken and formed during the reaction.First, let's analyze the structure of MBC  C5H8 . It has:- 4 C-C single bonds- 1 C=C double bond- 8 C-H bondsNow, let's analyze the structure of the polymer  C5H8 n. For every monomer unit in the polymer, there will be:- 4 C-C single bonds- 8 C-H bondsNotice that the C=C double bond in the monomer is broken and converted into a C-C single bond when the polymer is formed. Therefore, for every monomer unit in the polymer, there is one C=C bond broken and one C-C bond formed.Now, we can calculate the enthalpy change for the polymerization of 1 mole of MBC:H = [Bonds formed - Bonds broken] * Bond dissociation energyH = [ 1 C-C bond formed  -  1 C=C bond broken ] * Bond dissociation energySince the bond dissociation energy for a C-C bond is 348 kJ/mol and the bond dissociation energy for a C=C bond is approximately 2 * 348 kJ/mol  as it is a double bond , we can plug these values into the equation:H = [ 1 * 348  -  1 * 2 * 348 ] kJ/molH = [348 - 696] kJ/molH = -348 kJ/molThe enthalpy change for the polymerization of 1 mole of 2-methyl-1,3-butadiene  MBC  is -348 kJ/mol. This means that the reaction is exothermic, as energy is released during the polymerization process.