Galvanic vs. Electrolytic Cells

by Jules Bruno
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Hey guys, in this new video, we're going to continue with our discussion off our galvanic cell with one that spontaneous and see the connection between our K R Delta G and our new value self potential, the E value. So let's take a look at this question. It says, Ah, certain electrochemical cell involves a five electron change. So here I'm telling you, how many electrons are going to be canceled out. So and here equals five and has a value of K Q equal to 3.0 times 10 to the 16 at 2 98 Kelvin. The value of Delta H for the reaction is negative. 68.3 kg per mole. Calculate the values off Delta G, Delta E and for standard electrochemical cell constructed. Based on this reaction and also Delta s for the reaction. So we have a lot of variables we have to look at. Well, here I give us our K value. Remember, if we know okay, we conform a connection between K and with our e value, which we're gonna just refer to it as our SSL. Remember, the equation that connects them together is SL under Standard State conditions. That's what the zero means equals. Rt over. Number of electrons transferred Her changed times. Faraday's constant times. Allen of K. So let's plug in what we know Our is our constant, which is 8.314 Jules over most times K. Our temperature is already in Calvin. I gave it to his 2 98 Kelvin so we can plug that in the number of electrons changing or being transferred US five and then Faraday's constant remember, that's a constant. It doesn't change here. What's 96,500 is a rough approximation to be more accurate. It's 96,000, 485 cool ums over moles of electrons. And this five is five moles of electrons. Mhm, remember, see up Top is cool ums and columns is just charge And then we're gonna do the l n off 3.0 times. 10 to the 16. That's r K value. We plug all that in and we're gonna say the units for S L R volts volts. So he will be 0.195 volts. Okay. And remember, when we're talking about volts, one vault is equivalent toe one. Jewell over one. Cool. Um, so just remember that for later on, that's what one volts equals. So we just found our e value. If we know our e value, we confined our delta G value because they're connected by this equation. Delta G zero equals negative end times. Fair days, constant times R s. L remember. And is the number of electrons transferred, so five moles of electrons transferred. Faraday's constant is 96,485 school ums over moles of electrons. Yeah. Remember, we just said that vaults are jewels over columns. Right. So this is 0.195 jewels oversee cool apps. And in that way, we can see all the units getting canceled out, and we can see why air units are what they are. So moles of electrons cancel out cool apps. Cancel out. Our units will be left in jewels. Okay, so you plug all that in. That gives us negative 94,000 73 jewels. So so far, we found our SL. We found out Delta G. Finally, we have to find our Delta s. Remember, we know Delta G. We know Delta h. We confined Delta s because the equation that connects them all together is Delta G zero equals Delta H zero minus t Delta s zero. So now, technically, our Delta H is in killing jewels. So we should change our delta G also to kill jewels. So this will be negative. 94.73 killer tools equals negative 68 0.3 Killah Joel's over moles times temperatures to 98 Kelvin multiplied by s and actually subtracting 2 90 Calvin. And that's multiplying with Delta s. So we need to isolate Delta s. So we're gonna add 68.3 to both sides. And we're gonna say that answer we're gonna divide by the negative to 98 Kelvin. So when you add those two together, that gives us yeah, 25.77 29 killer jewels and will be negative and he calls negative to times Delta s divide both sides by negative to Kelvin, the negatives council out. So our answer at the end is gonna be a positive. Okay, it's gonna be 0. killer jewels over Kelvin's and this small shouldn't be there. And that right that will represent your Delta s. So remember, we have to remember what formulas connect the different variables together. So this one connects our s a with R K. This connects our delta G with R s. L remember we could also used We could have also said Delta G equals negative rt times L a N k that would have connected us between Delta G and with our K value. So we could have used this first, actually, if we wanted Thio in order to go from the K that I gave you the question directly to Delta G. So remember, these are different equations. All of them connect them to one another as long as you could remember those formulas. You remember the connections that you have between one variable and another variable. Now that we've seen this, I want you guys to attempt to answer this question here, I give you the e values for two half reactions and I want you to figure out what chaos now remember. All we have to remember here is the larger e value means that reduction is occurring. The larger e value means reduction reduction happens at the cathode the smaller e value means oxidation is occurring. And if oxidation is occurring, that must be your an ode. And remember, how do you find your overall e? You're East cell value. It's what Minus what? Once you find that variable, that answer for S l remember. What's the connection between SL and K? What equation do we use? Once you know the equation to use, then it's your job toe. Isolate K. Don't worry. If you get lost, just come back and watch the next video and I'll show you how to approach this problem. Good luck, guys.