E˚ values help

[ineedhelp2]

Hi everyone,

Would anyone be able to explain E˚ values and potential difference to me? I've read the textbook many times, but when I encounter exam questions they ask for things not addressed in the textbook.

What exactly do E˚ values mean? And also in regards to 2010 Chemistry exam 2 question 6a and b (about electrolysis), how did they come about those conclusions?

Link: http://www.vcaa.vic.edu.au/Documents/exams/chemistry/2010chem2-w.pdf

Thankyou very much !

[Lejn]

In this case of the question it is important to note that a strong oxidant being reduced will give the greatest Eš value, and the strongest reductant being oxidised will give the lowest Eš value. By what we are told, only one of the cells in subject was reduced, so we can deduce that it was the strongest oxidant, and therefore has the highest Eš value, so we assign it that.

For the second part of the question, we only know that the other two cells are weaker oxidants than the standard cell. We don't know anything about their reduction or oxidation capabilities relative to each other, only to the standard cell. As a result, we can't assign either value to each one.