Mass Transfer
In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when

Saturated feed is not used
An azeotrope forms
The latent heat of vaporisation of the more and less volatile components are greatly different
A total condenser is used

ANSWER DOWNLOAD EXAMIANS APP

Mass Transfer
In an operating distillation column, the

Vapors and liquids are at their dew point and bubble point respectively
Highest temperature is encountered at the top of the column
Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column
Driving force for the liquid flow is its specific weight

ANSWER DOWNLOAD EXAMIANS APP