1.) What is the value of E o for this half reaction using copper/copper(II) as t

Question

1.) What is the value of Eo for this half reaction using copper/copper(II) as the reference electrode in volts (V)?

2.) What is the balanced chemical reaction for this voltaic cell? A coefficient of 0 means that the species doesn't show up on that side of the equation.

___Au(s) + ____ Au3+(aq) +  

___Au(s) + ____ Au3+(aq) +  

___Cu(s) +_____ Cu2+(aq)

4.) What is the number of electrons transferred from the reactants to the products in the above balanced chemical equation?

5.) What is the expression for Q from the above balanced chemical equation? Remember that a negative exponent will put that value on the bottom of the expression.

6.) We are now going to use the Nernst Equation (shown below) based on the above balanced chemical equation information

to find the concentration of Au3+(aq) in mol/L in the following voltaic cell.

Cu(s)|Cu2+(aq, 0.025 M)||Au3+(aq, xx M)|Au(s)          Ecell = 1.170 V

If you can please explain each problem, thank you.

Explanation / Answer

Q1.

if we use Au as reference

then

Au3+ + 3 e Au(s) +1.52

Cu2+ + 2 e Cu(s) +0.337

then..

Ecell (measured) = Edifference - Ereference

since Ereference is that of gold (Au) then,

Ereference = -1.52

Eread = ?

ECopper = 0.337

substitute

the Ecell read = 0.337 -1.52 = -1.183 V

note that in reality, tthe comparison between potentials is the same, they just changed reference values

for gold, Eval = 0 (in this reference state vs. 1.52 in the H+ state)

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