Question 25

[royal_eccl3096]

I don't really understand why the silver electrode is positive. I think that I'm thinking that the silver Ag is being reduced and therefore gains electrons making it negative.

Thanks for the help.

[Guest]

Correct, the Ag is reduced however the electrode is a positive cathode at the reduction half cell since the electrons are moving from the Fe2+.Thus, essentially at the cathode it is positive because the reduction reaction takes up electrons and the ions that are being reduced are from the solution and the reduction is occurring on the surface of the half-cell.

So essentially, the Ag+ is from the silver ions in solution that are being reduced at the surface of the Ag electrode. Hence, the way to look at the cathode half cell as being + is by visualizing the electrons being released from the anode half cell redox reaction (negative half cell) towards the cathode end in which the electrons need to go towards an opposite charge thus, positive cathode end. Opposites attract. Remember the positive charge on the cathode end is due to the positive ions in solution (Fe2+).

[jsfkt78927]

I got this one wrong bc i didnt know what voltaic was - either galvanic or electrolytic.

it didnt say galvanic, so i assumed electrolytic.

is it common for the mcat to use voltaic rather than galvanic?