Question

A) Compute the repeat unit molecular weight of polystyrene. B) Compute the number-average molecular weight for a polystyrene for which the degree of polymerization is 25,000.

Answer 1

Step-by-step explanation:

In Polystrene, the molecular formula for the repeat unit =
`C_8H_8`;

and the atomic weights of Carbon C = 12.01 g/mol

For Hydrogen, it is 1.01 g/mol

Hence, the repeat unit molecular weight is:

m = 8 (12.01 g/mol)+8(1.01 g/mol)

m = 96.08 g/mol + 8.08 g/mol

m = 104.16 g/mol

The degree of polymerization = no-average molecular weight/repeat unit molecular weight.

Mathematically;

`DP = (\overline M_n)/(m)`

`\overline M_n= DP * m`

`\overline M_n= 25000 * 104.16 \ g/mol`

`\overline M_n= 2604000 \ g/mol`