Final answer:
To find the expected number of repeat units (n) per chain in chain addition polymerization, calculate the moles of monomer and initiator using their respective masses and molar masses and then divide the moles of monomer by the moles of initiator.
Step-by-step explanation:
The question relates to the calculation of the number of repeat units (n) in a chain during a chain addition polymerization process. Given the mass of the monomer and the mass and molar mass of the initiator, one can calculate n by first determining the number of moles of monomer and initiator present. The number of moles of monomers that can be polymerized per mole of initiator gives the degree of polymerization, which corresponds to the value of n. To calculate this, use the formula for moles (moles = mass / molar mass) for both the monomer and initiator and then divide the number of moles of monomer by the number of moles of initiator. The answer reflects the expected number of repeat units per chain assuming 100% conversion and no termination effects.
To illustrate with the provided information, the moles of monomer are calculated from its mass (4.54 grams) and molar mass (68.7 g/mol), and similarly, the moles of initiator from its mass (109 mg or 0.109 grams) and molar mass (190.5 g/mol). With these values, the degree of polymerization is found and represented as: n = moles of monomer / moles of initiator.