Question

Predict the products for the following reactions. If no reaction will occur, write NR. Remember to balance all reactions and include states of matter.

1.) Cu^2+ (aq) + Au (s) -->

2. Ni^2+ (aq) + Na (s) -->

Answer 1

The reactions are Cu+2 (aq)+2e----->Cu Eo=0.337V (1)

Au+ (aq) e-------------->Au , EO=1.68 V

multiplying with 2 and reversing the reaction gives 2 Au----------> 2Au(s) + 2e-              Eo=-1.68V (2)

addition of 1 and 2 gives Cu+2(aq) + 2Au-(s)--------> Cu(s) Eo= 0.337-0.168 =1.343 V Since

deltaG= -nFE, the reactino is spontaneous

b) The second reaction

becuae Na+ + e-          ---------------> Na (s) EO= =2.714 V

Na (s)------------> Na+ +e-              Eo= 2.714 V

multiplying by 2 gives 2Na ---------> 2Na+ + 2e- Eo= 2.714 V

Ni+2 + 2e-          -------------. Ni Eo= -0.25V

when added gives 2Na + Ni+2 ------->2Na+ + Ni Eo= 2.714-0.25= 2.646 V

since deltaG= -nFE is -ve, the reaction is possible.