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GOB Chemistry
Learn the toughest concepts covered in your GOB - General, Organic, and Biological Chemistry class with step-by-step video tutorials and practice problems.
Table of contents
Classification & Balancing of Chemical Reactions2h 41m
So galvanic cell, also known as a voltaic cell is a spontaneous cell that produces or discharges electricity. Therefore making it a battery. Now we're gonna say it uses stored chemical energy and converts it into electrical energy. Now it has different parts to it. First we're gonna talk about the an ode. The note is known as the negative electrode when it comes to a galvanic or voltaic cell. So it's the metal electrode and compartment where oxidation occurs. Remember oxidation means that you are losing electrons. The cathode is the positive metal electrode and compartment where reduction occurs. Remember that means you're gaining electrons. So if you look at this image here, we have basically the anote here which we labeled in this aqua blue. So it's negatively charged cathode is positively charged. The anna is losing electrons. So it's literally losing electrons from its surface. The electrons are going this way towards the cathode. The cathode is this metal electrode here. So this electrode is gaining electrons. This one here is losing electrons. The one that's losing is zinc, zinc solid. In this case it also has dissolved in it, zinc two plus ions which are originating from the cap on the electrode itself. Over here we have copper two plus ions in the solution which are originating from this electrode as well. Now we also have what's called a salt bridge. A salt bridge is a tube that connects both half cells. So a half cell is this jar and this jar, both half cells to one another and allows for the flowing of neutral ions. Now, neutral ion sounds a little bit like an oxymoron, like ions have a charge. So why would they be neutral? Well when we say the term neutral ions were basically saying these are ions within solution that possess no acidic or basic properties. Okay so ions when we're getting to this electrochemical stuff, they can be acidic, basic or neutral here. When it comes to our galvanic or voltaic cell we use neutral ions within this salt bridge this tube here. This tube here has within it negative ions and positive ions that are neutral ions. The negative ones will flow towards the annual compartment. The positive ones will flow towards the cathode department compartment. Now besides that, we have one more piece the volt meter. The volt meter which is this portion right here. This is device that records the amount of electricity generated by the galvanic cell. So this thing here is actually producing electricity which is pretty cool. It does it by a spontaneous redox reaction. So just remember when it comes to galvanic or voltaic cells, same thing. These are the important portions of it. And it also depicts the flow of electrons as we move from the an ode to the cathode
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example
Galvanic Cell (Simplified) Example 1
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the purpose of the galvanic cell is to a purify solids be allowed for only oxidation seen, generate electricity or d to consume electricity. Alright, so no. Where did we talk about purifying solid through the process of a galvanic or voltaic cell? So this would be out now. Galvanic cell utilizes a redox reaction, A spontaneous redox reaction in order to generate or create electricity. Remember, redox reactions involve both reduction and oxidation. It wouldn't only be oxidation and in defining and describing a galvanic slash voltaic cell, I said that they produce or create electricity. So they're generating electricity to say they're consuming electricity is the opposite. Remember a galvanic, which is the same thing as a voltaic cell. They're just batteries they're making or discharging electricity. Okay, so it's being used. Uh they're just using it. So they're a battery at the end of the day. So, the answer here will be options.
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example
Galvanic Cell (Simplified) Example 2
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now, before we can answer the example question, let's just go through what's happening on a visual level between the electrodes of zinc and copper. All right. So here we said that zinc represented the A node. And remember we said the note is where oxidation occurs under oxidation. Your oxidation number should increase zinc solid which is shown here. It is losing electrons. And in the process coming off of the whole metal electrode to produce these zinc two plus ions within solution, you're gonna say zinc is oxidized Tuesday two plus. So here that would translate to no reaction of zinc solid Gives Me Zinc two Plus. And if we're to balance this half reaction, we'd add electrons of the more positive side. So the zinc solid side is neutral with no electrons no charge. The Zinc two Plus side has a plus to charge. We got two electrons to this side. Then we'd say copper is the catheter where reduction occurs or gaining electrons. So this metal electrode surfaces gaining electrons, making the surface more negative. That would attract some of these copper two plus ions that are floating within a solution. So they come by and attach themselves to this negatively charged surface and thereby neutralise their charge and become um just copper solid on top of the already metal electrode. So how would that look? Well, we'd say here for that one. We have our reduction occurring. So we'd say C2 plus is reduced to see you. So we'd have see you two plus Acquis gaining two electrons and in the process become copper neutral. So copper solid, we cancel out the electrons. And then what comes down is our overall reaction which is zinc solid plus copper two plus Acquis Gives us Zinc two plus a quiz. Plus copper solid. So this would be the redox reaction that's formed in terms of this galvanic cell and now that we've gone through all the steps that are involved, we can answer this example question where it says how many electrons are transferred between the zinc and copper electrodes in the galvanic cell. So we say here the elections that are cancelling out our two electrons. So you say there are two electrons that are being transferred um in this process, in terms of zinc and copper electrodes for this particular galvanic cell. So here the answer be option B.
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concept
Galvanic Cell (Simplified) Concept 2
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And electrolytic cell is a non spontaneous cell that utilizes electrolysis in order to operate. Now, electrolysis is when we have chemical reactions that consume external cam electrical electrical energy in order to occur. Now we're going to stay here no matter the cell, whether it be an electrolytic cell, a galvanic slash voltaic cell, it doesn't matter. The cathode is always the site of reduction and the A note is always the site of oxidation. However, because electrolytic cells are non spontaneous, their signs will be different here. Since the process is non spontaneous, the cathode is now negatively charged, indiana is now positively charged. So basically our understanding here is that when it comes to electrolytic cells, they are the opposites of galvanic cells. So just remember this fundamental idea, they're opposites of one another.
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example
Galvanic Cell (Simplified) Example 3
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Here, it states, identify the location with an electrolytic cell where the loss of electrons will occur. Alright, so loss of electron means that we are undergoing oxidation. Yeah. Now remember, it doesn't matter what type of cell we're dealing with, whether it be an electrolytic cell. A galvanic cell will take. Cell. Oxidation always occurs at the A node, reduction always occurs at the cathode, so again, loss of electrons will occur at the anodes. That means that option B is the correct answer.
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concept
Galvanic Cell (Simplified) Concept 3
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So when it comes to an electrolytic cell it has to consume electrical energy and then it converts that energy into chemical energy. Now because an electrolytic cell requires electrical energy. You typically see a battery being installed with an electronic self so they can draw this electrical energy out and quickly converted into chemical energy. Now remember in electrolytic cell are cathode is now negatively charged and the A note is positively charged. But even though their signs are different, we still have to realize that when it comes to the cathode, that is where reduction occurs. So here 10 2 plus ion is still reduced but now to 10 neutral and notice still oxidation. So now copper metal is oxidized to copper two plus. We still have our salt bridge, we still have the movement of electrons now. So electrons will move this way towards my cattle. So that's not going to change. Alright, so now we're going to say that since we're dealing with the cathode, we have R. S. N two plus acquis being reduced to be reduced, it has to absorb electrons. So it's going to have to electrons To give us our 10 neutral solid and then are an ode is being oxidized with losing electron. So we have our copper solid here losing two electrons To produce copper two plus acquis. When we cancel out the electrons, what we get is our overall equation, which is S. N two plus Aquarius plus copper solid, gives me S and solid plus copper two plus acquis. And we're gonna say here, is that the application of an electrolytic cell? Is that we see that it can be used for batteries. So we can have example double A, triple A. Etcetera batteries. We use those batteries to harness electrical energy and convert it into chemical energy. We could also utilize rechargeable lithium batteries. Mhm. So, just remember electrolytic cells are non spontaneous and so requiring outside energy source. This application is in the form of batteries. We utilize the electrical energy that they can produce, converted into chemical energy that we can deal with redox reactions.
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example
Galvanic Cell (Simplified) Example 4
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here, it says which of the following is true about an electrolytic cell. It changes chemical energy into electrical energy. No. What is the exact opposite? It harnesses the electrical energy from batteries and uses it to make chemical energy. It uses a positive cathode. Remember in this case, the cathode is negatively charged, not positive. It uses an electrical current to make a non spontaneous reaction. Go. Electrolytic cells are non spontaneous. They can't do the process naturally without the use of outside energy. Okay, So they're gonna have to siphon off this electrical energy from batteries. Use that energy to make themselves go and occur. So this year is true. He can't be all of the above because options A and B. We found were not true. So here we're going to say electrolytic cells are non spontaneous. As a result, they require an outside energy source Here. It happens in the form of batteries. We harness that electrical energy and use it to convert into chemical energy.
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Problem
Which of the following statements is true for a salt bridge?
A
Contains neutral atoms that interact with the ions in both half-cell compartments.
B
Serves as a route through which ions can flow freely.
C
Serves as the site of oxidation.
D
Serves as the site of reduction.
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Problem
Which of the following statements is TRUE for a voltaic cell, but FALSE for an electrolytic cell?
I. The flow of electrons is spontaneous. II. Oxidation occurs at the anode. III. Electrons flow from the anode to the cathode.
A
Only I
B
I and II
C
II and III
D
I, II, and III
E
Only II
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Problem
What is the balanced half reaction that occurs at the anode in the overall cell reaction of a voltaic cell?