How do I know if an allergic reaction will occur again?

Will the following reaction occur? If so, predict the product and balance.?

• Hello guys! I have trouble determining whether or not a reaction will occur. I know the answer is no reaction but I want to know how to figure that out by myself. What exactly should ...show more

• Answer:

  First of all, the coefficients don't disappear. The reaction should read 2Al^3+(aq) + 3Zn(s) ==> 3Zn^2+(aq) + 2Al(s) To decide whether this reaction occurs as written, look at the reduction/oxidation potentials of both half-reactions. Oxidation: Zn ==> Zn^2+ + 2e- . . .Eo = +0.76 V Reduction: Al^3+ + 3e- ==> Al . . . Eo = -1.66 V E cell = E ox + E red = 0.76 + (-1.66) = -0.90 V Since E cell is negative, this reaction will NOT go in the direction written. The opposite reaction has an E cell of +0.90 V and is spontaneous.