Chemical Forums

Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: inspiration100 on January 24, 2008, 08:16:55 PM

Title: Activity Series Question [why Li is ahead of K]?
Post by: inspiration100 on January 24, 2008, 08:16:55 PM
Title pretty much says it all.  I'm confused why Lithium is ahead of Potassium on the activity series.  When you put Potassium in a bucket of water, it has a much more vigerous reaction that Lithium.

Can anyone explain why Lithium is ahead of Potassium? 
Much appreciated!
Title: Re: Activity Series Question [why Li is ahead of K]?
Post by: enahs on January 24, 2008, 08:31:19 PM
Now that you say it like that, I see why I was having trouble helping you with the previous question. On my activity series I have here, it is not. But a quick search on the internet turns up that most charts lists Lithium higher the Potassium, but not all.

I would be curious if other people have any publications (books) to compare it with the majority of the internet that does put Li higher.

Title: Re: Activity Series Question [why Li is ahead of K]?
Post by: inspiration100 on January 24, 2008, 08:50:21 PM
Both my general chem book and the internet sources state Li is ahead of K.  Thats why i'm confused.
Title: Activity Series Question [why Li is ahead of K]?
Post by: Riyafa on September 01, 2010, 03:26:59 AM
I have come across the same problem;
Li is said to be more reactive than K, but why Li is placed at a higher position than K in the activity series?
PLEASE REPLY
Title: Re: Activity Series Question [why Li is ahead of K]?
Post by: tamim83 on September 01, 2010, 08:45:47 AM
I looked at Siska's "University Chemistry", which has Li ahead of K in the activity series.  Dr. Siska wrote that this goes against intuition (based on ionization energy trends) but this ordering also takes bonding and/or solvation energies into account.  So, if it takes more energy to solvate a K+ ion than a Li+ ion (K+ does have a higher enthalpy and free energy of formation than Li+ in aqueous solution but I don't have solvation energies handy), than it would be more favorable for Li to displace K in solution.