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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. Sides covered with foil. Tube completely covered with foil. Uncovered. Hexane and Bromine. Start.
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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.
Sides covered with foil Tube completely covered with foil Uncovered
Hexane and Bromine Start At different times the foil is removed and a photograph is taken 10mins 20mins 30mins
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.
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.