Ewokinarmor

Hey everyone, this isn't strictly a homework problem but I'm curious about electrochemistry, went a bit ahead in my book, and I found something that doesn't seem to add up. Could you help me please? Okay, so I was looking at the enthalpy change from the reaction of the Daniell Cell and found that its around -210 kJ, a value that agrees with the net ionic equation (when I looked up standard enthalpies of formation for Cu2+ and Zn2+): Cu2+(aq) + Zn(s) -> Zn2+(aq) + Cu(s) But here's my problem: the first and second ionization energies of Copper add up to 2702kJ/mol. If it takes 2702kJ to ionize one mole of Copper into Cu2+ (that is, remove the first two e-) then shouldn't that be the standard enthalpy of formation for Cu2+? If I apply that logic to Zn2+ then its standard enthalpy of formation should be 2639kJ/mol and the enthalpy for the reaction should be 2639 - 2702 = -63 kJ. Neither of the two enthalpies of formation that I predicted are true and neither is my predicted enthalpy of the reaction. What did I do wrong? Does it have more to do with electron affinity than ionization energy? What DOES determine the enthalpy of formation of ions?

Hey, I read ahead a little bit in my chemistry book and came across the table of standard reduction potentials. Is it possible to increase the reduction potential of, say, a metal by stimulating it with an electric current? Because if what I know of electric currents is true (they're net movements of electrons), then shouldn't the electrons in the current have enough energy to jump from the metal and reduce other things that normally would not accept an electron?

Hey, I know that trying to put lithium or any alkali metal in water would result in hydrogen gas and an explosion, but is it possible to dissolve small amounts of the regular 1s^2 2s^1 form in a solvent that wouldn't react so violently? I mean, it wants to give that valence electron away, so could a solvent shell form around the lithium atoms (if they were unbonded) even if it technically doesn't have a charge? That probably sounds a bit jumbled, so here's a hypothetical scenario to better illustrate the question: A lithium atom with all its original protons and electrons intact is put inside a liquid solvent that is made up of a molecule that has a + side and a - side(much like water's "hands and feet"), but no hydrogen. Will a solvation shell be formed around the atom, since it wants to get rid of that valence electron so badly (and maybe the positive ends of the solvent will be attracted? But wouldn't that just form a partial shell around the area where the electron is?). Thanks, I hope none of that sounded too weird. I haven't formally taken chemistry yet, but I have a basic knowledge of it.

Alright, thanks guys! Sounds fascinating, can't wait for AP Chem

Hey, just a hypothetical question (I haven't been able to take Chem yet, but I do know the basic aspects of chemistry, so sorry if I sound like an idiot here). I'm not talking about any specific acid here, so let's just say it's submerged in H+ ions. My uneducated guess is polypropylene, as it appears to be the most nonpolar. Sorry about what is perhaps a stupid question, but any answers would be greatly appreciated.

Hey guys. I am thinking of creating something relating to batteries (sorry, no specifics!), but since I have not yet formally taken chemistry or any electrical classes, this is, understandably, problematic. Don't get me wrong though, I'm not going into this blindly. I have taken AP Bio, so I have a good understanding of the periodic table, the elements, valence electrons, redox reactions, electronegativity, Endergonic vs. Exergonic, etc, etc. I have been trying lately to get a good understanding of how batteries work, but there are still a few things that confuse me. Here's what I know so far: A battery consists of an anode (negative I think, like ANion, but the charts I see are never consistent), a cathode (+, like CATion?), and an electrolyte between them. Electrons are passed from the negative side to the positive side through the electrolyte, and a wire or other conductor is used to get this charge out of the cell to do work. When most or all of the electrons have done this, the battery is depleted. However, what really confused me was the Daniell Cell. If the point here is to send electrons from one side to another, then why does there seem to be a separate path for electrons and a separate path for ions? Don't the ions have to carry the electrons? What role do the ions and the salt bridge play, if not to shuttle electrons from - to +? Thanks, and sorry for the pretty large post. Here's a link to the diagram in question: http://en.m.wikipedia.org/wiki/Daniell_cell#/image/File:Galvanic_cell_labeled.svg