sapling week 7/8 #12

[LexyDenaburg_3A]

Calculate the standard free-energy change for the reaction at 25 ∘C.

Refer to the list of standard reduction potentials.

2Au3+(aq)+3Zn(s)↽−−⇀2Au(s)+3Zn2+(aq)

How is delta G calculated in this question?

[StephanieIb]

-write the half‑reactions.
3Zn (s) ⟶3Zn2++6e−
2Au3+ (aq) +6e−⟶2Au (s)

Use a table of standard reduction potentials to determine the overall cell potential.
E knot cell=(1.498 V)−(−0.76 V)=2.26 V

Use the equation deltaG(knot)=−nFE(knot)cell.
with n=6, F being 96485J, and E(knot)cell=2.26
plug all of these values into the equation to get your final answer of -1310

[Samantha Low 3D]

First, find the E°cell=E°cathode - E°anode

Then, use the equation deltaG°= -nFE°cell, where n is the moles of e- transferred and F is faraday's constant 96485 J/(V*mol). Hope this helps!

[Nayra Gharpetian 3F]

first fin E°cell using the standard reduction potentials given. then use the equation ΔG°=-nFE°

[Arnav Saud 2C]

For this problem, the first thing you want to do is find the reduction potential values of the anode and cathode.
You then want to use the E = cathode - anode.
After you find that, you want to use the delta G = -n*F*E equation.
Also, note that n = moles of electrons are transferred in this reaction.

[Deivy Gonzalez 3H]

I was having trouble with the units of parts like Faraday and E. This cleared things up, thank you.

[Madeline Zhang 3D]

For me, the most confusing part of this equation was the number of electrons that needed to be transferred.

You need to take in the number of electrons being exchanged by using the 1. oxidation numbers and 2. the amount of mols in the reaction.
At first, I tried to calculate the free energy with mols of electrons based on their sign if they were being reduced or not. For this equation, it seems like the sign does not matter and to just use a positive integer for the equation.

Finally, when finding your solution, keep in mind that Faraday's constant is in J vs kJ. The answer is asking for kJ. I hope this would be helpful!