If 200 g of benzoyl peroxide are used with 38 Kg of PTFE monomer, calculate the expected molecular weight of the polymer if (i)

Question

3 years ago

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all the termination occurs by combination (ii) all the termination occurs by disproportionation. Assume 15% efficiency for the initiator.

1 answer:

den301095 [7] · Answer 1 · 2022-01-01T05:18:14+03:00

Explanation:

The molecular weight of benzoyl peroxide is 242.23 g/mol.

Therefore, number of moles present in 200 g of benzoyl peroxide are as follows.

No. of moles = $\frac{mass}{\text{molar mass}}$

= $\frac{200 g}{242.23 g/mol}$

= 0.825 mol

Molecular weight of PTFE is 100 g/mol.Hence, calculate the number of moles of PTFE in 38 kg as follows.

As 1 kg = 1000 g. So, 38 kg = 38000 g.

No. of moles = $\frac{mass}{\text{molar mass}}$

= $\frac{38000 g}{100 g/mol}$

= 380 mol

As it is given that the initiator is 15% active. So, actual number of moles of benzoyl peroxide are as follows.

$0.15 \times 0.826$

= 0.124 mol

For combination, 1 mol of benzoyl peroxide produces 1 chain. Therefore, degree of polymerization will be calculated as follows.

DP = $\frac{380 mol}{0.124 mol}$

= 3065.33 mol

Average molecular weight of monomer is as follows.

$\frac{0.124}{0.124 + 380} \times MW_{benzoyl} + \frac{380}{0.124 + 380} \times MW_{PTFE}$

= 100.05 g/mol

Therefore, calculate the expected molecular weight of polymer as follows.

$3065.33 \times 100.05 g/mol$

= 306675.23 g/mol

Hence, for disproportion 1 mole benzoyl peroxide produces 2 chains.

DP = $\frac{2 \times 380}{0.124}$

= 6129.03

Therefore, calculate the expected polymer weight as follows.

$6129.03 \times 100.05$

= 613209.68 g/mol

Thus, we can conclude that the the expected polymer weight is 613209.68 g/mol.