Generally, the larger the evaporating flask the greater is the evaporation rate. This is due to the greater turbulence inside a larger flask, enlarging the active surface and leading to a higher evaporation output. On the other hand, smaller flasks are advantageous when the residue needs to be collected for further quantitative analyses. Moreover, larger flasks generally allow easier handling.
Achieve higher distillation efficiency when using a rotary evaporator – Impact of flask size