in my experiment we got an unknown sample where we first separated the mixture using column chromatography, and then used TLC so we can determine the Rf values for the 2 separated components of the mixture and a unseparated mixture.
i was wondering if the purpose of using column chormatography is just to separate teh components of teh mixture, and then TLC is used to determine the Rf values?
thanks!!
TLC is an analytical technique – it tells you how many compounds are in the mixture (in your case, two). Rf values tell you how far each of those two components move up on the TLC plate.
But in order to physically separate the two compounds in the mixture, you need to use column chromatography. In this case, TLC can help you figure out which compound will come out of your column first – the one that moves up higher on the TLC plate (larger Rf value) will come out of the column first.
TLC/column chromatography gives you an idea of the relative polarity of the two compounds: the one that comes out of the column first (meaning the one that moves up higher on the TLC plate) is the less polar compound.
why is it better to change from a less-polar solvent to a more-polar solvent rather than the opposite?
A more polar solvent will move non polar compounds too.
This is because the silica or alumina you are using as the stationary phase is polar – hence polar compounds stick well and non-polar compounds not so well. So that means that as long as the non-polar compound is soluble in the solvent it will move; and for the vast majority of the time your non-polar compounds will be soluble in your polar solvent (especially at the ratios involved in chromatography).
Hence starting will the polar solvent will just make everything come off as the start.
I just got this guitar today..and its not what i was looking for..I mean the guitar looks cool, but the sound wasnt what I wanted..im thinking of taking it back and getting a different guitar..the reason I dodnt like it was because im those type of people who listen to heavy metal and like distortion..and this guitar’s sound sounded soo weak to me…I tried playing some heavy stuff, but it sounded terrible…anyways..what should i exchange it for?
Keep in mind that Squire is Fenders student line, but that doesn’t mean anything is wrong with it.
It is probably your amp settings. If your amp doesn’t allow "overdrive" or "distortion" then you need to have an amp or effects box that reproduces what you want.
How about THIS novel idea… if you learn to play "clean" first your efforts in the heavy metal arena will sound MUCH better. There are many heavy metal guitarists that played classical music first then moved to dirt and distortion.
whenever electron enters the atom, energy is released. In other words the first electron affinity has a negative value because energy is released. why is energy released?
Perhaps the easiest way to grasp this is to look at the opposite first. Take sodium, electron structure 2.8.1. To remove the outer orbit electron [1st ionization energy] you must pull it off .. ie put in energy, positive value.
So with chlorine, ES 2.8.7 you are doing the exact opposite. Cl atoms attract an extra electron to achieve the ES of the nearest rare gas 2.8.8 and energy is released. 1st EA is negative value.
Have a look at
http://www.chemguide.co.uk/atoms/properties/eas.html
http://www.chemguide.co.uk/atoms/properties/ies.html
where these terms are well explained
Three great adaptations
Here’s a video of me playing a stock Squier Affinity Telecaster through the Nocturne Brain Seltzer into a Danelectro Reel Echo and finally through a VOX AC15CC1 (with Wharfdale, not a Blue speaker). EQ was set at noon across the board with no reverb or tremolo and the knobs on the Nocturne were positioned at 3:00 and 4:00.
For the entire review, go here: http://5th-fret.blogspot.com/2009/11/tavo-vega-brain-seltzer-nocturne-review.html
-Pappy
http://www.5th-fret.blogspot.com
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How to use Affinity Diagrams to group ideas – this is a great tool to use in brainstorming sessions to capture discussion points and put into groups to see trends.
For more business improvement tools and methods including lean and six sigma visit http://www.valuestreamguru.com or follow us at http://www.twitter.com/valuestreamguru
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So you get enough, but not too much of the sample. 
"Europeans fight because of different political ideas and black people fight because of tribal affinity "
Agree or disagree and why?
Europeans don’t fight because of tribal affinity?LOL
Are you rejecting the Chechnian massacre? And what about the hate between Russians and Ukranians? Or the long a*s feud between the french and the british?
Introduction of high-quality and high-grade GC columns for gas chromatography. A direct comparison against HP and DB columns.
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