Question

Z-average molar mass $\left({\overline{M}}_z\right)$ is defined as:

• A. $\frac{\sum NiM{i}^2}{\sum NiMi}$
• B. $\frac{\sum NiMi}{\sum Ni}$
• C. $\frac{\sum NiM{i}^3}{\sum NiM{i}^2}$
• D. $\frac{\sum NiM{i}^3}{\sum NiMi}$

Answer 1

The correct option is C $\frac{\sum NiM{i}^3}{\sum NiM{i}^2}$

Z-average molar mass $\left({\overline{M}}_z\right)$ is defined as $\frac{\sum NiM{i}^3}{\sum NiM{i}^2}$

where Mi is the molecular weight of a chain, Ni is the number of chains of that molecular weight, and i is the number of polymer molecules