1. Electrochemistry Solving a problem you’ve never seen before and for which you have no formula. Produced by Mr. Doddridge Murrieta Valley High School

2. What’s the most important thing in chemistry? Units Keeping Mr. D happy! Units

3. Keeping Mr. D. happy! This is a good thought. Although it is very important, it’s probably only #2. Try again

4. Right! So let’s proceed to a problem keeping this in mind and not panicking Proceed (next)

5. Question: How much copper can be plated in 30 minutes at 10 amps? (Cu +2 + 2e - → Cu) What are we being asked? What unit? Were you thinking: grams?

6. What are some facts you know? 1 amp = 1Coulomb/second 1Faraday = 96485 Coulombs/mole e - Mass of copper = x g/mole (What’s x ?) (Where would you find it?) Were you thinking: the periodic table?

7. Do you remember the question? How much copper can be plated in 30 minutes at 10 amps? (Cu +2 + 2e - → Cu) The facts: 10 ampsin 30 minutes 1 amp = 1 C/s 1 F = 96,485 C/mole e - 1mole e - = how many moles Cu? (Cu +2 + 2e - → Cu) 1 mole Cu = X grams Cu?

8. What’s the given? = 30 minutes10 amps or given

9. What’s the given? 10amps = 10 coulombs/ second This might work, but let’s try dealing with the time first. = 30 minutes10 amps

10. Good! Now what goes here? 30 min = sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/

11. Try Again. Remember: units must cancel 30 min = sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/

12. Good! Now what goes here? sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec =

13. What will cancel “seconds”? sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec =

14. Good! Now what goes here? 1 sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10Coulomb =

15. Hint: I shortened Coulomb to C sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10Coulomb =

16. Good! Now what goes here? sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10Coulomb = 1 Coulomb 1 mole e-

17. Come on now! We’re almost finished. sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10Coulomb = 1 Coulomb 1 mole e-

18. Stop kidding around! sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10Coulomb = 1 Coulomb 1 mole e-

19. Finally! Now what could possibly go here? sec10 Coulomb/1 min60 sec/ 96,485 C/1 mole e - 1F= /2 mole e- 1 mole Cu (s) 63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) =

20. Care to try again? 1 mole Cu(s)63.5 g Cu/ 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) =

21. Alright! So, what’s the answer? 23.7 g Cu 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) 63.5 g Cu = 5.92 g Cu or

22. Calculator error. Try again. 23.7 g Cu 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) 63.5 g Cu = 5.92 g Cu

23. Right! Remember the question? How much copper can be plated in 30 minutes at 10 amps? We were expecting an answer in grams. 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) 63.5 g Cu = 5.92 g Cu

24. Right! Remember the question? How much copper can be plated in 30 minutes at 10 amps? We were expecting an answer in grams. Click here to see how things cancel. 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) 63.5 g Cu = 5.92 g Cu

25. Right! Remember the question? How much copper can be plated in 30 minutes at 10 amps? We were expecting an answer in grams. And that’s the only unit that didn’t cancel. 30 min 1 min 60 sec 1 sec 10 Coulomb 96,485 C 1 mole e - 2 mole e- 1 mole Cu (s) 63.5 g Cu = 5.92 g Cu

26. Want to try some more? Click below to go to a site where you can get more practice More Practice