(b) Given
the following reduction potentials, calculate the standard
emf of the cell:
Cd1OH221s2 + 2 e- ¡ Cd1s2 + 2 OH-1aq2
E°red = -0.76 V
NiO1OH21s2 + H2O1l2 + e- ¡ Ni1OH221s2 + OH-1aq2
E°red = +0.49 V

Question

(b) Given 
the following reduction potentials, calculate the standard 
emf of the cell: 
Cd1OH221s2 + 2 e- ¡ Cd1s2 + 2 OH-1aq2 
E°red = -0.76 V 
NiO1OH21s2 + H2O1l2 + e- ¡ Ni1OH221s2 + OH-1aq2 
E°red = +0.49 V

Accepted Answer

Hello everyone. So in this video we're trying to determine the standard E. M. F. Generated by the battery. So we're given this overall reaction as well as the half reactions and the standard reduction potentials. So first things first is to kind of break down this process. So we know that the cathode, this is where the reduction occurs. So the oxidation number decreases. And then at the anodes is of course it's just the opposite of a cat though. So this is where the oxidation occurs and this is when the oxidation number increases. So we have of course our balance de created right over here and we're gonna go ahead and analyze this. So for br two in this liquid state, the natural elemental state, uh the oxidation number is zero. So oxy number is equal to zero and then for our zinc in its solid state Which is the natural elemental state. The oxidation number is again zero. And then we're looking at the products that we have our bro main an ion and there's a negative one charge. So the oxidation number is going to be negative one. And then for our zinc cat island has a charge of two plus. So the oxidation number is going to be oxy number is equal to plus two or positive two. So we see here for the grooming that the oxidation state is being changed from zero to negative one. So the oxidation number decreased or the oxidation number has decreased. So we have a reduction and that happens at the cathode. So let's go ahead and actually put that. So we see here at the B R oxi number is decreased. It's reduced and this occurs at the cathode. For these inc we can see that the oxidation number is changing from zero to positive two. So the oxidation number has increased, meaning that it's been oxidized. And this occurs at the A note. So zinc oxy number went up. It is being oxidized and this occurs at the anodes. So if a balanced reaction equation is not given to you, you can go ahead and determine the ana cathode by comparing their E values, which is the standard reduction potentials. So these values are given to us. So if we have a lower reduction potential, then this is the oxidation and it occurs at of course the anodes. And if the reduction potential is greater or bigger than the other, comparing half cell reaction, then the reduction is occurring. And it happens at the cathode. So, given the cell potentials for each of the have our actions. So I'm just gonna go ahead and rewrite these two half reactions. So we have the zinc solid going to let's see the end two plus, which is a glorious. And then of course those two electrons and then our browning its liquid state with the two electrons going to to roman minus that is a twist, we kind of take the some of this. And of course by hess's law, the two electrons will cancel. So our remaining equation will be the browning to liquid plus the zinc solid. To give us to be R minus which is Aquarius plus the zN two plus, which is of course, and it's moving down here. So now we're gonna go ahead and calculate for our E cell, do it over here on the right, so the sl is equal to the E catheter minus, R E a node plug in the values that are given to us in the hassle reaction already. And the problem, the e cathode is one oh 71. volts minus a negative 0.76 volts. So, putting this into my calculator, I get that my sl will equal to 1.83V. So then my final answer for this problem is that my S. L. is equal to 1.83V.

(b) Given the following reduction potentials, calculate the standard emf of the cell: Cd1OH221s2 + 2 e- ¡ Cd1s2 + 2 OH-1aq2 E°red = -0.76 V NiO1OH21s2 + H2O1l2 + e- ¡ Ni1OH221s2 + OH-1aq2 E°red = +0.49 V

Verified Solution

Key Concepts

Standard Electrode Potentials

Cell Potential Calculation

Oxidation and Reduction Reactions