OK, we now know why those particular chemicals are in chemtrails. But what do you think the purpose of chemtrails are?
Please feel free to add to these:
Weaken immune systems in vertibrates
Cause and exacerbate respiratory diseases
Heat or cool the atmosphere through the albedo effect
Create a mirror for high altitiude projections for audio, visual, wavelength, or high or low frequency modulation

Why go to the effort and expense just for these reasons?
It seems like there is a bigger purpose.