Drawing a correct slope (student errors)

Sometimes students get confused on exams when trying to draw line with a certain slope. In this video we reiterate how to interpret slopes and also go through a distillation example where the q-line is to be drawn in an x-y diagram (using McCabe-Thieles graphical method)

Time codes:
0:00 Intro
0:16 What slope is this
1:15 McCabe-Thiele example