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AP EAMCET · Chemistry · Polymers

The polydispersity index of a polymer containing 10 molecules with molecular mass \(1.0 \times 10^4\) and 10 molecules with molecular mass \(1.0 \times 10^5\) is approximately.

  1. A 1.67
  2. B 0.59
  3. C 1.55
  4. D 0.83
Verified Solution

Answer & Solution

Correct Answer

(A) 1.67

Step-by-step Solution

Detailed explanation

The PDI (polydispersity index) \(=\frac{M_w}{M_n}=1.67\) \(M_w=\) Weight average molecular weight. \(M_n=\) Number average molecular weight. \[ \begin{aligned} & M_n=\frac{N_1 M_1+N_2 M_2}{N_1+N_2}=55,000 \\ & M_w=\frac{N_1 M_1^2+N_2 M_2^2}{N_1 M_1+N_2 M_2}=91818 \end{aligned} \]