Polymerization Kinetics: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

Given polymer molecular weight distribution, calculate average molecular weight.

  1. Calculate number-averaged molecular weight.
  2. Calculate weight-averaged molecular weight.
  3. If molecular weight of repeat unit is 56, calculate the degree of polymerization.
table used in an example problem in the Polymerization Kinetics module on LearnChemE.com
Example Problem 2

Find the rate of propagation in terms of concentration of initiator and concentration of monomer using the steady-state approximation. The reaction steps are:

\[I \rightarrow 2R_c \boldsymbol{\cdot}  \]

\[R_c \boldsymbol{\cdot} + M \rightarrow RM_1 \boldsymbol{\cdot} \]

\[RM_1 \boldsymbol{\cdot}  + M \rightarrow RM_2 \boldsymbol{\cdot} \]

\[R_j \boldsymbol{\cdot}  + M \rightarrow R_{j+1} \boldsymbol{\cdot} \]

\[R_j + R_k \rightarrow P\]