A blend contains 6.0 g of one species of chain of $20000 g mo l^{- 1}$ and 6.0 g of another species of $60000 g mo l^{- 1}$ . Which are correct?

Answer: A, B, C

Moles:

6.0/20000 = 3.0 \times 1 0^{- 4}

and

6.0/60000 = 1.0 \times 1 0^{- 4}

M_{n} = 12.0/ (4.0 \times 1 0^{- 4}) = 30000

M_{w} = \sum N_{i} M_{i}^{2} / \sum N_{i} M_{i} = (6.0 \times 20000 + 6.0 \times 60000) /12.0 = 40000

. PDI

= 1.33

. 40000 is

M_{w}

, not

M_{n}