Chemistry
posted by Anon on .
X^2+ + 2e > X(s) E=1.73V
Y^2+ + 2e > Y(s) E=0.40v
Which pair of species would react under standard conditions?
X^2+ and Y^2+
X and Y^2+
X and Y
X^2+ and Y
Would it be X and Y because the E is positive?

I don't think X + Y will be positive. In fact they won't react at all.
X^2+ + Y ==> X + Y^2+ 1.730.40 = +? 
So would it be X^2+ and Y^2+?

No. How do you get a reaction out of X^2 + Y^2?
X^2+ + 2e ==> X
Y^2+ + 2e = Y
Both of them are being reduced. In a reaction an oxidation is ALWAYS accompanied with a reduction.
So X and Y won't react.
X^2+ + Y^2+ won't react.
The only possibilities are the second and fourth choices and I gave you the right choice in my first response.