1. A3.2 - Hexane and Bromine
Hexane and Bromine are mixed together in three tubes and each tube is then exposed to a different light level.

2. Sides covered with foil Tube completely covered with foil
Uncovered

3. Hexane and Bromine Start
At different times the foil is removed and a photograph is taken
10mins
20mins
30mins

4. Now watch a video clip to see what happens when a glass rod is used to dispense ammonia gas to tubes 1 and 3. Click on photo to start.

5. Questions
What evidence is there that bromine undergoes photodissociation?
Look up the values for Br-Br and C-H bond enthalpies. Remember that bond enthalpies are given per mole of bonds. Calculate the enthalpy change when (i) one Br-Br bond is broken, (ii) one C-H bond is broken. Use E=hv and calculate the frequencies of photons of radiation corresponding to each of these energies. Which bond is most likely to be broken by absorption of sunlight?
What has the bromine reacted with?
What is the gaseous product that is formed?
Write an equation, with state symbols, for the reaction of this gas with ammonia.