How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25ºC), which are miscible with each other?
We know that to separate two miscible liquids we use simple distillation or fractional distillation.
Simple Distillation - When difference in boiling point is more than 25ºC
Fractional Distillation - When difference in boiling point is equal to or less than 25ºC
Since the difference between boiling points of kerosene and petrol is more than 25ºC, we will use the technique of simple distillation.
Steps to Separate Mixture of kerosene and petrol by Distillation
- Mixture of Kerosene and petrol
- Distillation Flask
- Thermometer to Monitor Temperature
- Take the Mixture of Kerosene and Petrol in a flask
- Heat it
- Monitor the temperature with help of Thermometer
- When boiling point of petrol is reached, it converts into vapour
- However, kerosene is left in flask as it has higher boiling point
(Boiling Point of petrol is 95 degree celsius but that of kerosene is nearly 175 degree celsius)
- These vapours of petrol flow into the condenser where it gets cooled and converts into liquid again
- This liquid petrol is stored in the beaker while kerosene continues to remain in the flask
Hence, we are able to separate mixture of petrol and kerosene
Fig 2.9 NCERT Page 21 with heading Distillation