# AP Electrochemistry – what do you need to know…

The formula list that is part of your AP packet is here:

Yep, that’s it!

Depending on the equation sheet to help you out in an exam is never the best idea. Do memorize these equations. You do need to know the following:

- How to recognize an oxidation or reduction equation and how to write the half reactions.
- How to balance a redox reaction.
- What a Galvanic vs. Electrolytic cell is and all the parts therein.
- Be able to identify a cathode and anode in either of the above cells.
- Understand the processes that happen in the cathode, anode, salt bridge, etc.
- Calculate the cell potential, E, and understand what it means wrt spontaneity.

After you are comfortable with all the above, we can now relate E to * Δ*G by the first equation:

- Remember that
**Δ****G**also relates to the equilibrium constant.**K** - Now we have 3 parallel measures of spontaneity.
,**K****Δ****G**and.**E** **K>1**,**Δ****G****<0**and**E>0**for a spontaneous process.

In an electrolytic (** non spontaneous) **cell

*you will be often asked to find the amount of metal deposited when a current (*

**,****) is run through the cell for a certain amount of time. You then go through the following process:**

*I*** I (current)→q (charge)→moles_{e}→moles_{metal}→grams_{metal}** or the other way, as the question may be.

. This is what the equation on your sheet is for:**I → q**, the number of moles of electrons you have used. F here is the faraday’s constant, also in your equation sheet.*q/F = n*_{e}- Use your reduction equation here, eg.
*Al*. This shows a 3:1 molar ratio between^{3+ }+ 3 e^{–}→ Aland**n**_{e}**n**_{metal} - Find
using this ratio*n*_{metal} - Multiply by molar mass to find grams of the metal!

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