Perch
Chemistry 171
20 October 2014
Periodicity of the Halogens
Goal: To design and carry out an experiment that will give enough data to rank the three halogens from highest to lowest electron affinity.
Background: The three aqueous solutions given in this experiment are Iodine, Bromine, and Chlorine; they are all non-polar and dissolve easily in Hexane which is also non-polar. When there is a color change in a mixture that means that it reacted and that there was a double displacement reaction when there is no change then it didn’t react because it isn’t possible. Cl2 + 2NaBr Br2 + 2NaCl Cl2 + 2NaI I2 + 2NaCl Br2 + 2NaCl Cl2 + 2NaBr NOT POSSIBLE Br2 + 2NaI I2 + 2NaBr I2 + 2NaCl Cl2 + 2NaI NOT POSSIBLE I2 + 2NaBr Br2 + 2NaI NOT POSSIBLE
Procedure: Six flasks were obtained for the three substances each flask had 10 drops of Hexane in each then flasks 1 & 2 had 10 drops of Cl in them, 3 & 4 had 10 drops Br and 5 & 6 had 10 drops of I. Then in flask one 10 drops of sodium bromide were distributed into it. Next ten drops of sodium iodide were put into flask 2, followed by putting 10 drops of sodium chloride into flask 3 and 10 drops of sodium iodide into flask four. Afterwards 10 drops of sodium chloride and 10 drops of sodium bromide were put into flasks 5 & 6 respectively. A cork was placed on the top of each of these flasks so outside air wouldn’t interfere with the reaction and observations were made.
Data:
Test Tube
Color Change
BEFORE
AFTER
1
Clear
Yellow
2
Clear
Orange, Pink
3
Orange
No change
4
Orange
Brown, Dark purple
5
Pink
No change
6
Pink
No change
Conclusion: Electron affinity highest to lowest: Chlorine, Bromine, and Iodine. They are in this order because Chlorine reacted with both NaBr and NaI, Bromine only reacted with NaI and Iodine didn’t react with either of the other mixtures. Just the way how they reacted was how you could tell which was which. And