6L.7c HW

[Hannah Lee 2F]

6L.7 (c) Write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions:
Cd(s) + 2 Ni(OH)3 (s) --> Cd(OH)2 (s) + 2 Ni(OH)2 (s), the reaction in the nickel–cadmium cell

For the cell diagram, why is there a line instead of a comma between two solid species of the same phase? Also, why is OH- not included in the cell diagram for the cathode despite being a product?

I'm confused as to when you would exclude species from the cell diagram even if they are present in the half reaction. It is to my understanding that if the species are not involved in the reaction, they are not going to be present in the cell diagram; however, isn't OH- considered part of the reaction?

[Ryan Narisma 4G]

Hi Hannah Lee 2F! To answer your first question, the reason why there is a line in between the two solids is to differentiate between the metal electrode used in the cell from the solid involved in the reaction. OH- is present in the diagram as the base, KOH. I think it's the in anode half reaction cell due to the fact that when combined the hydroxide in the cathode cell would cancel out and leave 1 OH- in the anode cell. I hope this helps!