<p>When ur calculating the voltage of a cell, Ered</p>
<p>why is that you not take the opposite sign for the oxidation potential (when u look at the reduction potential chart)</p>
<p>For example, if...</p>
<p>Cu2+ + Zn -> Zn2+ + Cu
Ecell= 0.34 - (-0.76) = 1.10</p>
<p>Why wouldn't u take the opposite sign of -0.76 if its oxidation.</p>
<p>You do. If your looking at a reduction potential chart, but that ion is being oxidized in your cell, then you take the opposite sign of the electric potential.</p>
<p>no, thats not what my barron's ap book says >_<</p>
<p>assuming the formula is
E(red) -E (oxi)</p>
<p>bump bumpbb</p>
<p>Pretty sure it is E (red) + E (ox) = E(total)</p>
<p>Yeah, you add cell potentials.</p>
<p>If you wanted to use:
E(red) - E(ox) = E(cell),
then you wouldn't reverse the charge because you already are by subtracting the E(ox).</p>
<p>i dont think about it that way.
you always need to have a metal and an ion on each side and you wnat your Ecell to be the most positive value positive so you just manipulate the equations so that this is true. when ever you flip an equation you change the sign and the add both values.</p>
<p>LOL, my teacher taught it as E(red) - E(ox), too, then I read in the book that you flip it...</p>
<p>Guess who durn near failed her electrochemistry test?</p>
<p>Ecell= Eox + Ered. So when your given two reduction half reaction potentials, you flip the ox rxn. that's all you have to do. If they give you oxidation potentials, which they haven't done recently but I hear they can do to screw with your mind, you take the ox potential and the negative of the red rxn.</p>