Classify each reaction as an oxidation, a reduction, or neithe...

Question

Classify each reaction as an oxidation, a reduction, or neither.

(a)

(b)

(c)

Accepted Answer

Hey everyone and welcome back in today's video, we are going to label each of the following reactions as reduction oxidation or none of it. Now, we may notice that we have three different reactions which involve multiple steps and in order to answer this question correctly, we are going to look at the concept of an oxidation reduction reaction which is also defined as a redox reaction. Now you may recall that redox reactions involve an electron transfer. However, in organic chemistry, we must have some easier way to think about these reactions to clearly identify whether an atom was oxidized reduced or nothing really happened overall. So we are going to look at general guidelines that will definitely help us in determining whether and oxidation or a reduction reaction has occurred or maybe there was no change at all. So let's start with an oxidation reaction and generally we may emphasize several possible cases for an oxidation reaction. In organic chemistry. We definitely want to think about the addition of oxygen. So he may either have addition of oxygen or die atomic oxygen as well as addition of intelligence in the form of X. T where X is a halogen, such as chlorine, bromine or iodine. Also, we may think about oxidation from a different perspective, it may correspond to the loss of H two. Now, similarly, if we think about a reduction reaction reduction generally implies that we have an addition of hydrogen and in particular that atomic hydrogen age too. Right additionally, we can think of addition of high tried age minus and from the other perspective, we may think about the loss of oxygen as well as loss of halogen. In other words, you may notice that these processes are opposite. If oxidation had addition of oxygen or a halogen, then a reduction reaction will correspond to the loss of oxygen or a halogen. And similarly if oxidation had loss of hygiene, then reduction corresponds to addition of hygiene. Now, whenever we are thinking about neither of them, those would essentially imply several possibilities. We can have multiple reactions such as addition or loss of H plus, for example, H two. What are hi jen, hey light in the form of H. X and so on. So we are going to use these guidelines to understand what kind of reactions we are observing here. Now one of the easiest ways is to actually define the molecular formula if it's not really clear. So starting with with reaction a we are simply going to count the number of carbon auction and hydrogen atoms to see if we are losing or gaining some sort of an atom. So notice how we have 1234 carbon atoms. We can say that C four. Now, in terms of hydrogen, we have three plus two, that's five plus two. That's seven plus two, that's nine and plus one, that's 10. So we have 10 hydrogen atoms and one oxygen. So that's the molecular formula of the starting alcohol. Even though immediately, you may immediately recognize that chromium six oxide in the presence of Pepperdine is a good oxidizing agent that allows us to formaldehyde. So we can think about this as an oxidation reaction. Let's not worry about the region. And let's just think about The material that we are forming. And you may notice that you still have 1234 carbon atoms C4. The number of hydrogen atoms would be one plus two, that's three plus two, that's five and plus three. That's eight. Right? So we have eight hydrogen atoms and one oxygen and we can keep going again. We notice that this is an oxidizing agent, chronic acid. But let's not worry about it. Let's just count the number of carbon atoms, +1234. So that will be C four in terms of hydrogen atoms, that would be three plus 25 plus 27 plus 188 Hae jin's and t oxygen atoms. So, looking at this reaction, first of all, let's see what is the change hydrogen atoms and auction atoms. So auction atoms are the same. That's one oxygen atom, but we are losing two hydrogen atoms and you may recall that the loss of H T corresponds to oxidation. So we may state that the first reaction in a represents an oxidation stat. Similarly, if you think about the next reaction, you may notice that we have the same number of hydrogen atoms eight and eight on each side. But we are adding an oxygen atom. So we can say that for this step we are adding an oxygen atom and because we're performing an addition of oxygen That corresponds to oxidation. Once again right addition of oxygen or the loss of H2 corresponds to oxidation. We have another oxidation reaction. And you may notice that these are indeed consistent with our observation of these two regions. They are oxidizing agents. Well done. So let's use the strategy for B in B. We have a molecule of ethane. Notice how we have two carbon atoms 12 and the number of hydrogen atoms would be three plus two plus one. So that's six. Right? If we define the molecular formula for ethanol, that would be two carbon atoms. Then we have three plus two plus one. That's still six hydrogen atoms and one oxygen atom. Or the cookbook silic acid formed. Or in particular. That's acetic asset. We have 12 carbon atoms. So that B. C. To the number of hydrogen atoms would be three plus one. Right? That would be four and two oxygen atoms. Then for the corresponding al al hide ethanol formed, we have two carbon atoms. Right then in terms of hydrants, we have three plus one, that's four and one oxygen. And finally for the newly formed asset which contains an alcohol group we have 12 carbon atoms. The number of hydrogen atoms will be one plus two. That's three plus one. That's four. And the number of oxygen atoms would be three. Now let's think about the net change from first react in the first reaction we are losing an oxygen atom right? Because we had six hydrants in each. But actually we're adding an oxygen atom. My apologies. You may notice how we didn't have an oxygen atom and now we have one oxygen atom. Now from the second structure to third one, we noticed that We are losing to hydrogen is right? So we are losing H two and we are adding oxygen. Now looking forward, we essentially noticed that the number of hydrogen Xyz not changing, but we are losing an oxygen atom. And finally for the last one, the number of hydrogen atoms is the same. But we are adding two oxygen atoms are basically can think about it. S. 02. So now let's think about it for the first reaction. If we have an addition of oxygen that corresponds to oxidation. Now for the next one we are removing hydrogen and removal of hygiene corresponds to oxidation and in addition we are oxidizing again, we're adding oxygen. So we are completely oxidizing our alcohol in two different ways. Right? We're oxidizing it completely recall that first of all, we oxidize our alcohol to an al the hide and then we go from Aldo hide to a carb oxalic acid. That's why we have T oxidation stops and this reaction once again corresponds to an oxidation reaction. Now for the next one we have a loss of oxygen. A loss of oxygen corresponds to reduction. For the next reaction we are adding 02. An addition of 02 corresponds to oxidation. Well done. So we have our answers for B. And finally, let's look at sea, which might seem a bit more complicated, but let's not worry about it. We can just think about molecular formula of the starting material. That'd be 123456 carbon atoms. So we can label this as C six. The number of hydrogen atoms would be three plus two, that's five plus one, that's six plus one, that's seven plus one, that's eight plus one, that's nine. And then we have two more. That's 11 and then three more, that's 14. So we have H 14 and two oxygen atoms from the two alcohol groups, and the final material has carbon atoms, 32, that's five plus two plus two, that's nine plus three, that's 12 hydrogen atoms. And then we have one oxygen atom. You may notice that in this reaction. First of all, we are losing two hydrogen atoms. So we can say minus H two, but at the same time we are also losing one oxygen. You may notice that the starting material has two oxygen atoms and the final material has one oxygen atom. So you may notice that this reaction in wolves oxidation first of all because the first one has the loss of hygiene which corresponds to oxidation, right? And then it has the loss of oxygen which corresponds to reduction. So the two steps provide us with no change. There is no net change because from one perspective it's an oxidation reaction. From the other perspective, it's a reduction reaction. The first carbon atom is essentially oxidized and the other one is reduced. Right? So we can say that this reaction is neither of them. And the reason for that is because we observe an oxidation at one carbon atom and reduction and the other. So we can say that this is neither. Let's label our answers. So for a we may label our reactions as oxidation for the first step and oxidation for the second one. So both reactions are oxidation for B, we have oxidation followed by oxidation followed by reduction and an oxidation again, and C is neither actually, it would be more accurate to say that in C we are observing an oxidation at one position and reduction at the other and that there is no net change. Okay, so this is another perspective, looking at that there is no net change because one carbon atom undergoes oxidation and the other one undergoes reduction. But in this reaction, overall that these two cancel each other out as one reaction if we essentially analyze as a one possible reaction. So, to conclude the correct answer to this multiple choice question is C. However, if you have any questions, don't hesitate to leave a comment down below and thank you for watching.

Classify each reaction as an oxidation, a reduction, or neither.
(a)
(b)
(c)

Key Concepts

Oxidation and Reduction Reactions

Chromic Acid Oxidation

Hydration and Dehydration Reactions

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