Two unlabelled organic samples are believed to contain cyclopropane and propane.By means of one chemical test,show how the two compounds can be distinguished?
set both samples (at atmospheric pressure) in a dry ice box, once the both gases are liquified, remove them. The first to boil will be propane (bp -45F), followed by cyclopropane (bp -25F)
Add Br2 IN THE DARK. Cyclopropane will add Br2 in the dark to form the bromopropane. Propane will do this but ONLY with UV (or sunlight) and not in the dark.
See what great help you get on Jiskha. You get a means of identification PHYSICALLY and well as CHEMICALLY.
To distinguish between cyclopropane and propane, one chemical test that can be used is the reaction with bromine water. Here's how you can perform the test:
1. Take two separate test tubes and label them as Sample A and Sample B.
2. Add a small amount of Sample A in Test Tube A and Sample B in Test Tube B.
3. To Test Tube A, add a few drops of bromine water (a solution of Br2 in water).
4. To Test Tube B, add a few drops of bromine water as well.
5. Observe the color change in each test tube.
If Sample A contains cyclopropane, while Sample B contains propane, the following reactions will occur:
- Cyclopropane (Sample A) reacts rapidly with bromine water, turning the reddish-brown bromine water completely colorless. This is an indication of an addition reaction, where cyclopropane breaks the bromine-bromine bond ('Br-Br') to form 1,2-dibromopropane.
Cyclopropane + Br2 → 1,2-dibromopropane
- On the other hand, propane (Sample B) reacts slowly with bromine water. The color of bromine water fades more slowly compared to Sample A, turning into a lighter yellow color. This is due to the formation of 1-bromopropane.
Propane + Br2 → 1-bromopropane
Therefore, by observing the color change and the rate of reaction, you can distinguish between cyclopropane and propane using the bromine water test.