Question

why we cannot seperate two substance whoes boiling point differ by 25k by distillation method (Not frational distillation​

Answer 1

Answer:

Why is the difference of 25K only taken in fractional distillation?

Hey!

Fractional distillation is a technique in which you can separate two or more substances with small difference in boiling point.

Now the small difference depends upon how much pure substance you want.

As per your question, if the difference is more than 25 K(suppose 75K), then simple distillation is sufficient for the separation. There is no need for fractional distillation.

If the difference is less than 25 K(suppose 10K) then fractional distillation becomes useless until your apparatuses are highly accurate. In this case, you have to exploit other aspects of the two substances you need to separate.