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Cracking hydrocarbons

Description

In this experiment the vapour of liquid paraffin (a mixture of saturated hydrocarbons) is cracked by passing it over a heated catalyst. The mixture of gaseous short-chain hydrocarbons produced is collected and tested for unsaturation with bromine water. This experiment models the industrial cracking process which is important due to human demand for fuel.

Type of Activity

:
demonstration, class practical

Audience

:
Teacher

Age Group

:
14 to 18 years

Credits

:
This is an experiment from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry.
cracking-hydrocarbons


or class practical


Apparatus Chemicals

Eye protection

Safety screens

Each working group requires:
 
Test-tubes, 4

Bungs, to fit test-tubes, 4

Test-tube rack

Boiling tube (Note 1)

Bung, one-holed, to fit boiling tube

Delivery tube fitted with a Bunsen valve (Note 2)

Small glass trough or plastic basin, for gas collection over water

Bunsen burner

Heat resistant mat

Stand and clamp

Dropping pipette

Wooden splint

Medicinal paraffin (Liquid paraffin) NOT the fuel, about 2 cm3

Porous pot or pumice stone fragments (Note 3)

Bromine water, 0.01 M - diluted to a pale yellow-orange colour (HARMFUL), about 2 cm3

Acidified potassium manganate(VII) solution, about 0.002 M, about 2 cm3

Mineral wool (preferably 'Superwool')

Refer to Health & Safety and Technical notes section below for additional information.

 


Read our standard health & safety guidance






In this experiment the vapour of liquid paraffin (a mixture of saturated hydrocarbons) is cracked by passing it over a heated catalyst. The mixture of gaseous short-chain hydrocarbons produced is collected and tested for unsaturation with bromine water. This experiment models the industrial cracking process which is important due to human demand for fuel.

ADDITIONAL INFORMATION

This is a resource from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures. Practical Chemistry activities accompany Practical Physics and Practical Biology.

The experiment is also part of the Royal Society of Chemistry's Continuing Professional Development course: Chemistry for non-specialists