What is the cell potential for the reaction mg(s+fe2+(aq? mg2+(aq+fe(s at 77 ? c when [fe2+]= 3.40 m and [mg2+]= 0.210 m . express your answer to three significant figures and include the appropriate units?

First, you need to calculate the standard cell potential using standard reduction potential from a textbook or online. Since Mg becomes Mg+2, magnesium is being oxidized because it is losing electrons, you need to flip its potential

Fe+2 + 2e- --> Fe                  potential= -0.44
Mg+2 + 2e- --> Mg                potential= -2.37

Cell potential= (-0.44) + (+2.37)= 1.93 V

Now, you need to use Nernst formula to get the answer. I have attached a PDF with the work.

The teacher is mostly talking about the distillation of a mixture