Post-Lab Multiple Choice Questions

Toluene is a known aromatic compound. If you observed no change in the color of the bromine solution in test tube F (containing toluene) after 15 minutes, what can you conclude?

• Toluene has a higher boiling point than cyclohexane and cyclohexene, affecting the reaction rate.

• Aromatic compounds like toluene are more reactive towards bromine than alkenes under these conditions.

• The black sugar paper used on test tube A prevented the reaction from occurring.

• Toluene, unlike alkenes, does not undergo an addition reaction with bromine at room temperature.

Which of the following observations would strengthen the conclusion that the disappearance of the reddish brown color is due to a reaction between bromine and the organic compound?

• A white precipitate forms at the bottom of the test tube after 15 minutes.

• The solution in the test tube feels warm compared to others after 15 minutes.

• A gas is produced when the bromine solution is added to the organic compound.

• The reddish brown color disappears more slowly in test tubes kept in the dark compared to those in sunlight.

Test tube B was kept in sunlight along with cyclohexene. If you observed a persistence of the reddish brown color of bromine solution in test tube B after 15 minutes, compared to test tube D, what can you determine?

• Light accelerates the reaction between bromine and cyclohexene.

• Sunlight decomposes cyclohexene, preventing its reaction with bromine.

• The absence of light hinders the reaction between bromine and cyclohexene.

• Dichloromethane is not an effective solvent for this experiment.

You observed a complete disappearance of the reddish brown color of bromine solution in test tube D after 15 minutes. Which of the following is the MOST LIKELY explanation?

• The reaction between bromine and cyclohexene (in test tube D) is endothermic and requires light for the reaction to proceed.

• Bromine reacts readily with all hydrocarbons under these conditions.

• Cyclohexene (in test tube D) is an alkane and does not react with bromine.

• Cyclohexene (in test tube D) is an alkene and readily undergoes an addition reaction with bromine, causing the disappearance of the reddish brown color.

Based on this experiment, which property can differentiate between alkanes and alkenes?

• Boiling point

• Density

• Presence of double bonds

• Solubility in water