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by Charlyn Ghoubrial 2I
Sun Mar 15, 2020 7:45 am
Forum: Administrative Questions and Class Announcements
Topic: Constants and Equations
Replies: 1
Views: 21

Re: Constants and Equations

I’m pretty sure you’ll be given the info you need on the final
by Charlyn Ghoubrial 2I
Sat Mar 14, 2020 7:13 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.57
Replies: 2
Views: 30

Re: 5.57

I’m pretty sure you would use an ICE table. Find out the molarity of what you can and plug in the rest to the ice table
by Charlyn Ghoubrial 2I
Fri Mar 13, 2020 12:16 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams: single vertical line between two solids
Replies: 5
Views: 81

Re: Cell Diagrams: single vertical line between two solids

Dr Lavelle answered this question a few years back and said “you separate chemicals in different phases using a single vertical line and if you have multiple chemicals in the same phase (say 2 aqueous solutions) you separate them with a comma. Then, you separate cathode and anode by using a double ...
by Charlyn Ghoubrial 2I
Fri Mar 13, 2020 12:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Week 10 Review Problems (pg.7)
Replies: 2
Views: 35

Re: Week 10 Review Problems (pg.7)

Some solution guides have contradicting ideas but Dr Lavelle mentioned that species in the same state are separated by commas so I would just trust him on that
by Charlyn Ghoubrial 2I
Fri Mar 13, 2020 11:34 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Week 10 Review Problem
Replies: 2
Views: 21

Re: Week 10 Review Problem

For cell potentials, you only reverse the signs if you reverse the equation (without multiplying by coefficients) because it’s an intensive property that’s independent of stoichiometric coefficients. For enthalpy you and entropy, since they’re extensive properties, you reverse signs when reversing t...
by Charlyn Ghoubrial 2I
Tue Mar 10, 2020 8:51 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.15
Replies: 2
Views: 25

Re: 6N.15

I’m pretty sure you use Ecell= Ecell*+(0.592V/n) x pH
Your Ecell* is 0, n=2, pH=11
by Charlyn Ghoubrial 2I
Mon Mar 09, 2020 10:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n=2
Replies: 7
Views: 33

Re: n=2

N is the number of electrons that you cross out from both sides of the reduction and oxidation half reactions after you balance them
by Charlyn Ghoubrial 2I
Mon Mar 09, 2020 10:14 pm
Forum: Balancing Redox Reactions
Topic: balancing reactions
Replies: 6
Views: 27

Re: balancing reactions

The organic chemistry tutor breaks it down really well. Some people prefer khan academy so you could try both but i personally understand more from the organic chem tutor
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:44 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6N.7 (b)
Replies: 2
Views: 19

Re: 6N.7 (b)

H is going from either 0 (because it’s by itself) to +1 and viseversa so only 1 electron is being transferred
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:41 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3
Replies: 2
Views: 26

Re: 6L.3

You would flip the half reaction from appendix 2B (flip products and reactants) and flip the sign as well
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:38 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6.L.7 b
Replies: 1
Views: 18

Re: 6.L.7 b

I think it’s because your product is already H2O and everything is balanced except O2 so you add it to the left to balance on the right. Otherwise you would unnecessarily keep adding H+
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:35 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Exercise 6N 1b
Replies: 2
Views: 30

Re: Exercise 6N 1b

I think that’s a typo because ln goes from 3+ to 2+ and U goes from 4+ to 3+ so in both cases, one electron is being transferred but I’m not 100% sure
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:32 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum in cell diagrams
Replies: 5
Views: 25

Re: Platinum in cell diagrams

Pt is added to any side that does not have a solid conductor so whenever you only see (aq) or (g) or no solid conductor, add Pt
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:27 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Half/Rxn & Balanced Equations for galvanic cells.
Replies: 8
Views: 37

Re: Half/Rxn & Balanced Equations for galvanic cells.

It just implies that none of your species are solids. They’re either (aq) or (g) if you’re talking about example d
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:19 am
Forum: Balancing Redox Reactions
Topic: 6L.7
Replies: 1
Views: 32

Re: 6L.7

So you have to use the equation given to figure out the 2 half reactions you would use. One half reaction equation is your oxidized one (anode) and the other half reaction is your reduced one (cathode). When writing out cell diagrams, your anode always goes on your left and your cathode goes on your...
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 2:02 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.7
Replies: 5
Views: 54

Re: 6M.7

Sorry this question is about 6M.3... Can someone briefly explain the process for 6M.3? I just want to make sure I have the right concepts down Use the equation Ecell= Ec - Ea ( Ecathode - Eanode) and then figure out the standard reduction potential of each anode and cathode and then plug them in th...
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 1:56 am
Forum: Calculating Work of Expansion
Topic: 4A.3
Replies: 9
Views: 123

Re: 4A.3

Angela Patel 2J wrote:Also, how would we know the sign of the internal energy?


If energy enters the system: +
If energy leaves the system: -
If work is done on the system: +
If work is done by the system: -
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 1:50 am
Forum: Balancing Redox Reactions
Topic: 6k.5
Replies: 3
Views: 52

Re: 6k.5

I’m not entirely sure but since Br goes from -1 to +5 we know that this reaction is being oxidized so we just assume that O3 to O2 is being reduced I guess. But I don’t think O3 should pair up with BrO3- because that would put O2 with Br- and i don’t think that we can work with a half reaction like ...
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 1:40 am
Forum: Balancing Redox Reactions
Topic: Half rxns
Replies: 27
Views: 213

Re: Half rxns

Acidic: split equation in 2 half reactions and balance them (adding H2O to balance Os and H+ to balance Hs) then you cancel out your balanced electrons and anything else that needs cancelling and write your balanced equations Basic: same steps as Acidic but then you add OH- on the side that has H+ t...
by Charlyn Ghoubrial 2I
Thu Mar 05, 2020 1:30 am
Forum: Balancing Redox Reactions
Topic: Oxidation number
Replies: 5
Views: 49

Re: Oxidation number

The most ones you need to know for this class are: Any element standing by itself (unattached to another element) is always 0 O2 (when attached) is almost always 2- (H2O2 is an exception: O2 is -1) H is always +1 And from there you can figure out the rest from looking at equations The organic chemis...
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 11:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3 e
Replies: 1
Views: 17

Re: 6L.3 e

If I’m looking at the correct question, your half reaction for oxidation (at anode) should be Sn^(2+) —> Sn^(4+) +2e- and your half reaction for reduction (at cathode) should be Hg2Cl2 + 2e- —> 2Hg + 2Cl- So then your overall balanced equation after you cancel out the 2e- will be Hg2Cl2 + Sn ^(2+) —...
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 11:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams: single vertical line between two solids
Replies: 5
Views: 81

Re: Cell Diagrams: single vertical line between two solids

Dr Lavelle answered this question a few years back and said “you separate chemicals in different phases using a single vertical line and if you have multiple chemicals in the same phase (say 2 aqueous solutions) you separate them with a comma. Then, you separate cathode and anode by using a double l...
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 11:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt?
Replies: 2
Views: 18

Re: Adding Pt?

When the anode or cathode does not have a metal (all aqueous)
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 11:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7 Part A
Replies: 1
Views: 23

Re: 6L.7 Part A

I would just look at the appendix. The half reactions would be
Reduction: Ag+ + e- —> Ag
Oxidation: Ag + Br- — AgBr + e-
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 11:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6.43
Replies: 3
Views: 24

Re: 6.43

It is Ecell
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 9:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3D
Replies: 3
Views: 41

Re: 6L.3D

Your half reactions should be
Reduction: O2 + 2H2O + 4e- —> 4OH-
Oxidation: 2H2O —> O2 + 4H+ + 4e-
Cancel out the O2, 4e-
Balanced equation: 4H2O —> 4H+ + 4OH- which reduces to H2O —> H+ + OH-
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 8:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L
Replies: 2
Views: 26

Re: 6L

I don’t think you have to find Ecell. Just find the half reactions and the balanced equation for each
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 8:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.7
Replies: 5
Views: 76

Re: 6M.7

A lot of people have also been asking similar questions and it seems like no one really knows so either Dr Lavelle will provide us with the information on the test or I’m just going to try to see if there is a pattern to which one to use from all the questions and answer key in the textbook
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 7:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.1
Replies: 5
Views: 69

Re: 6M.1

An easy way to do this problem is to use the equation Ecell=Er-El
Ecell= E(Cu^(2+)/Cu) - E(M^(2+)/M)
E(M^(2+)/M)= (-0.689+0.34)V = -0.349V
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 7:21 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Knowing if a Metal will dissolve
Replies: 1
Views: 9

Re: Knowing if a Metal will dissolve

If delta G is negative, your reaction will be spontaneous so the metal will dissolve and if delta G is positive, your reaction isnt spontaneous so the metal will not dissolve
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 7:08 pm
Forum: Balancing Redox Reactions
Topic: 6L.5 (part d)
Replies: 2
Views: 35

Re: 6L.5 (part d)

I’m actually not sure. My half reactions were
Reduction: Au+ + e- —> Au
Oxidation: Au+ —> Au^(3+) + 2e- and it worked out at the end but idk if I’m right
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 3:43 am
Forum: Balancing Redox Reactions
Topic: hw 6l7c
Replies: 1
Views: 34

Re: hw 6l7c

You would use the half reactions:
Reduction: Ni(OH)3(s) + e- —> Ni(OH)2(s)+ OH-(aq)
Oxidation: Cd(s) + 2OH-(aq) —> Cd(OH)2(s)+ 2e-
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 3:36 am
Forum: Balancing Redox Reactions
Topic: 6K 5 part a)
Replies: 1
Views: 34

Re: 6K 5 part a)

Your oxidation half reaction would start as Br- (aq) —> BrO3^(-) and then you would balance the oxygen by adding 3H2O(l) molecules on the left
Your reduction half reaction would start as O3(aq) —> O2(g) and then you would balance the oxygen by adding H2O(l) molecule on the right
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 3:11 am
Forum: Student Social/Study Group
Topic: Test 2 Homework Problems, Etc
Replies: 6
Views: 50

Re: Test 2 Homework Problems, Etc

I am a little confused too but read the textbook and try to do the examples they have within the sections and the hw problems and then go to workshops or step up sessions and office hours for clarifications. That’s what i do. Hope that helps
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 3:04 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: inert conductor
Replies: 2
Views: 17

Re: inert conductor

When the anode or cathode does not have a metal (s).
I don’t think we need to but I’m not entirely sure
And i think because one side is only aqueous so you’d need to add platinum as an electrode
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 2:57 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: predicting is metals will dissolve
Replies: 3
Views: 30

Re: predicting is metals will dissolve

If delta G is negative your reaction is spontaneous so the metal will dissolve
If delta G is positive your reaction is nonspontaneous so the metal will not dissolve
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 2:46 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 2
Views: 22

Re: 6M.5

I think the half reaction would be Hg2^(2+) + 2e- —> 2Hg because that's the one that would give you +0.79 (i used appendix 2B to get that)
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 2:34 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6o.3
Replies: 1
Views: 29

Re: 6o.3

I understand how to look at the table to find out whether the reduction potentials are a larger positive number for the metal ion or water, but I am a little confused on where to go after that. If the cathode has a really large negative reduction potential(which we don't want), doesn't that mean th...
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 2:23 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Study Advice
Replies: 73
Views: 3489

Re: Study Advice

Ok so none of the replies mentioned the organic chemistry tutor! He’s really good and I find him better than khan academy but you won’t always find all the topics you need but he’ll provide the best and easiest explanations to the topics you search. Watch his videos if you need the basics to be expl...
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 2:07 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6.53 of the homework
Replies: 1
Views: 14

Re: 6.53 of the homework

It would decrease the concentration of Cr^3+ which decreases standard reduction potential of cathode so the cell potential will decrease ( Ecell= Ered-Eox)
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 1:36 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3d homework question
Replies: 3
Views: 57

Re: 6L.3d homework question

The right side of the electrode is for reduction and the left side of the electrode is for oxidation so the half reactions are Oxidation (at anode): 2H2O —> O2 + 4H^(+) + 4e- Reduction (at cathode): O2 + 2H2O + 4e- —> 4OH- How do we know the oxidation reaction is H20 oxidizing to O2 and 4H+ when on...
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 1:27 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7 b)
Replies: 1
Views: 26

Re: 6L.7 b)

Oxidation occurs at anode and reduction occurs at cathode so the half reactions are:
Reduction (at cathode): O2 + 4H+ + 4e- —> 2H2O
Oxidation (at anode):4OH- —> O2 + 2H2O + 4e-
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 12:54 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3d homework question
Replies: 3
Views: 57

Re: 6L.3d homework question

The right side of the electrode is for reduction and the left side of the electrode is for oxidation so the half reactions are
Oxidation (at anode): 2H2O —> O2 + 4H^(+) + 4e-
Reduction (at cathode): O2 + 2H2O + 4e- —> 4OH-
by Charlyn Ghoubrial 2I
Mon Mar 02, 2020 12:08 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 4
Views: 60

Re: 6M.5

Your 2 half reactions would be
Reduction (at cathode): 2(NO3)^(-) + 8H^(+) + 6e^(-) —> 2NO + 4H2O (Ecell= +0.96V)
Oxidation (at anode): 6Hg —> 3(Hg2)^(2+) + 6e^(-) (Ecell= -0.79V)
by Charlyn Ghoubrial 2I
Sun Mar 01, 2020 11:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L 7
Replies: 1
Views: 34

Re: 6L 7

For b) oxidation occurs at anode and reduction occurs at cathode so then the reduction (at cathode) is O2(g) + 4H^(+) (aq) +4e^(-) —> 2H2O(l) and oxidation (at anode) is 4OH^(-) —> O2(g) + 2H2O(l) + 4e^(-)
by Charlyn Ghoubrial 2I
Sun Mar 01, 2020 11:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 3
Views: 39

Re: 6M.5

605324529 wrote:Determine the standard cell potential:
2NO3(-)(aq) + 8H(+)(aq) + 6Hg(l) -->3Hg2(+2)(aq) + 2NO(g) + 4 H2O(l)

Thanks!


To find the standard cell potential, write the half reactions first then subtract the anode cell potential from the cathode cell potential and you should get +0.17 V
by Charlyn Ghoubrial 2I
Sun Mar 01, 2020 11:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3
Replies: 3
Views: 24

Re: 6L.3

Don’t we only have to find the half reactions and balanced equations for this question? Do we need to calculate the cell potential as well?
by Charlyn Ghoubrial 2I
Sun Mar 01, 2020 10:56 pm
Forum: Balancing Redox Reactions
Topic: 6L.5d
Replies: 2
Views: 41

Re: 6L.5d

I think you originally did it right because if you multiply the 2 by the reduction half reaction, you would get 2Au^(+) + 2e^(-) —> 2Au and then your 2e^(-) would cancel on each side giving you an overall balanced equation of 3Au^(+) —> Au^(3+) + 2Au
by Charlyn Ghoubrial 2I
Sun Mar 01, 2020 10:46 pm
Forum: Balancing Redox Reactions
Topic: 6L.9
Replies: 3
Views: 58

Re: 6L.9

For the equations I got: MnO4^(-) + 8H^(+) + 5e^(-) —> Mn^(2+) + 4H2O and Fe^(2+) —> Fe^(3+) + e^(-)
So Mn would end up with a 2+ charge and Fe would end up with a 3+ charge if i did this correctly

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