safety precautions to be taken in fractional distillation of petroleum

jadelamlam

1. The problem statement, all variables and given/known data
My textbook states that one of the safety precautions to be taken in the fractional distillation of petroleum(in school laboratory) is using a small flame to heat the rocksil(rocksil is soaked with petroleum),and avoil using stationary flame for heating.
Can anyone explain?


2. Relevant equations



3. The attempt at a solution
I guess the reason of using a small flame is to avoid the breaking of test tube(test tube is used to hold the rocksil)?But I have no idea on why shouldn't we use a stationary flame for heating.

jadelamlam

I have attached a diagram.

Attached Thumbnails

 

chemisttree

You have a flammable distillate and small apparatus. What might happen if you heat too strongly?

jadelamlam

So it will burn?

chemisttree

Only if something bad happens. Think 'strong heat vs. gentle heat' in this small apparatus.