Cell Potential: Standard - Video Tutorials & Practice Problems
Get help from an AI Tutor
Ask a question to get started.
1
concept
Standard Cell Potential Calculations
Video duration:
1m
Play a video:
Here, we're going to say that our standard self potential is represented by the variable E not cell. Here it is the measure are the reduction potential. Our standard reduction potential. So E knot red in vaults between two half cells. So our catholic compartment and our animal compartment. You remember standard refers to the ions within the half cells having values of one molar, one atmosphere and A P equal to seven vaults is represented by capital V. It represents the amount of work done as the electron travels from one electrode to another. Here, volts is also units equal to units of joules per cooler Coolum is a variable we've seen in earlier chapters. Coolum uses the variable capital C and it's just the si unit for electric charge. Now you're going to say that our standard cell potential of an electrochemical cell is calculated by the formula that it equals cathode minus anna. So remember an electrochemical cell is compo composed of two half cells. One being the cathode, one being in the ade if you can successfully determine which one is the cathode and which one is the a node simply use this formula here. And you'll be able to find your standard cell potential.
2
example
Standard Cell Potential Example
Video duration:
1m
Play a video:
Here it says what is the standard cell potential for a voltaic cell based on the following reduction reactions in which the copper electrode is the cathode and the zinc electrode is the Anno. All right. So here we have two half reactions. In the first one, we have zinc ion absorbing two electrons and becoming zinc solid. It has a standard reduction potential of negative 0.7621. Here, the units will be in volts. Then we have our copper reduction reaction where a copper two plus ion accepts two electrons to become copper solid. It has a standard reduction potential of 0.3394 volts. Now, within the question, I tell us that the copper electrode is the cathode and the zinc electrode is the Anno. From this point, we just remember that our standard cell potential so e not sell equals cathode minus anna. So plug them in. So 0.3394 volts minus a minus 0.7621 volts. Remember a minus of a minus really means they're adding, so add them together. When we do that, we get our final answer as 1.1015 volts as the voltage of our standard cell potential for this particular question, right? So again, 1.1015 volts would be our final answer.
3
concept
Galvanic Cell and Standard Cell Potential
Video duration:
1m
Play a video:
Now recall that a standard cell potential value that's greater than zero means the reaction is spontaneous. And when it comes to electrochemical cells, remember we have two types, we have our galvanic voltaic cell. Remember galvanic voltaic, they're synonymous with each other. You can use them interchangeably. And then we have our electrolytic cell. These are our two typical types of electrochemical cells. Now for galvanic voltaic cell, we're going to say that the cathode is the half cell compartment that has the higher standard reduction potential. And then the a node is the one that has the lower standard reduction potential. This results in a standard cell potential that is greater than zero. So this makes sense here because a galvanic or voltaic cell is a spontaneous electrochemical cell. So we'd expect it to have a cell potential greater than zero. The electronic cell. On the other hand, everything is kind of reversed here here. The calculator is now the one with the lower standard reduction potential. And the liano is the one with the higher standard reduction potential. Remember your standard cell potential is still cathode minus Anno because of this, the standard cell potential here will be less than zero, right. So just remember if we know the type of electrochemical cell that kind of guides us into what our standard cell potential should be at the end. And that's based on should the cathode have a higher or lower standard reduction potential or should it be the Anno knowing this is key to getting the right answer at the end. So keep this in mind when looking at the two types of electrochemical cells.
4
example
Standard Cell Potential Example
Video duration:
2m
Play a video:
Here, it says given the follow redox reaction, we have serum solid plus alumin ion reacting to produce aluminum solid plus sium aqueous. Here it says find its standard cell potential. When given the following half reactions. Here, we're given the half reaction for the serum three plus ion and the aluminum ion. Now, here, the steps that we take is first refer to the redox reaction to determine which species is reduced and which is oxidized. This is incredibly important because remember that the cathode is a site of reduction. So the cathode equals reduction and the a node is a site of oxidation. So the ade equals oxidation. Once we know this, we can use the standard cell potential formula to find our final answer. And that's because standard cell potential. So e not cell equals cathode minus atom. If we take a look here, we see that serum solid goes from zero for its oxidation state to plus three if oxidation number increased. Therefore, it has been oxidized. So here, if it's the site of oxidation, that means it must be the Anno and then if we look at aluminum aluminum goes from what it goes from plus three in terms of its charged slash oxidation state to neutral to its natural standard state, which is zero. So it goes from plus 3 to 0. Its oxidation number has been reduced or decreased. So reduction has occurred. Therefore, it is the Catholic. So we've determined the cathode and the anote and now we can find the standard cell potential. So take the values and plug them in. So for this will be negative 1.677 minus a minus 2.336. Remember a minus of a minus just means that you're adding them together. So negative 1.677 plus 2.336 gives me at the end 0.659 volts. This will represent the answer for my standard subpotent for the following example question.
5
Problem
Problem
Calculate the standard cell potential of an electrolytic cell when given the following half reactions.
Standard Reduction Potentials
Fe3+(aq) + e – → Fe2+ (aq) E°red = + 0.769 V
Li+ (aq) + e – → Li (s) E°red = – 3.04 V
A
–2.271 V
B
–1.551 V
C
–3.060 V
D
–3.809 V
6
Problem
Problem
Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.