Question

1 milliliter initiators solution in scrupulously clean and dry tetrahydrofuran containing 8.6 x 10^-4 mole of sodium and 9.4 x 10^-4 mole of naphthalene was injected into a solution of styrene(0.048mole) in 50 milliliters clean and dry tetrahydrofuran at -70°C. after a few minutes the reaction was complete. A few milliliters methanol was then added to quench the reaction and the reaction mixture was allowed to warm to room temperature. the polymer was recovered by precipitation. what is the Mn(number average molecular weight) of the polystyrene formed in absence of side reactions? What should the Mw(weight average molecular weight) the product be if the polymerization were carried out so that the growth of all macromolecules was started and ended simultaneously?

[Answer is suppose to be about Mn=11,300 and Mw=11,400... however I can't come up with that and I need help]

Answer 1

Step 1: Find out in the literature the Mn values of each polymer, in this case the styrene (400,000g/mol) and the tetrahydrofuran (3500g/mol).

Step2: We have to determine the Mn of the real quantity of styrene

As we know the tetrahydrofuran Mn only we have to add it with the styrene Mn

3500g/mo +19200g/mol =22700g/mol

Step 3: We have to know this equation

Step4: To know the Mw we have to determine the Mw of each polymer with his equation

Tetrahydrofuran

Styrene

Step5: we have to add all the values

Mw = 16240 + 525=16725g/mol