Question

If $N_1,N_2,N_3,......$ are the number of molecules with molecular masses $M_1,M_2,M_3,......$ respectively, the mass average molecular mass is expressed as?

• A. $\frac{\sum N_i{M_i}^2}{\sum N_i{M}_i}$
• B. $\frac{\sum N_i{M}_i}{\sum N_i}$
• C. $\frac{\sum {M_i}^2}{\sum N_i}$
• D. $\frac{\sum N_i{M}_i}{\sum M_i}$

Answer 1

The correct option is A $\frac{\sum N_i{M_i}^2}{\sum N_i{M}_i}$

Mass average molecular mass = $\frac{\sum N_i{M_i}^2}{\sum N_i{M}_i}$