What is the standard emf of a galvanic cell made of a Cd electrode in a 1.0 M #Cd(NO_3)_2# solution and a Cr electrode in a 1.0 M #Cr(NO_3)_3# solution at 25°C?
You first look up the standard reduction potential for each half-reaction.
Now, you convert one of these into an oxidation half-reaction by reversing the equation and changing the sign of
You choose the one that gives you a positive cell potential when you add the two voltages. In this case, you reverse the bottom one.