Electrostatic potential maps of acetic acid (CH₃CO₂H) and ethyl a...

Question

Electrostatic potential maps of acetic acid (CH₃CO₂H) and ethyl alcohol (CH₃CH₂OH) are shown. Identify the most acidic hydrogen in each, and tell which of the two is likely to be the stronger acid.

Electrostatic potential map of acetic acid (CH₃COOH) showing molecular structure.

Accepted Answer

Welcome back everyone. The following figure shows the electrostatic potential maps of the molecules, acetic acid and tri fluro acetic acid determine the most acidic hydrogen in each molecule and compare their acidity and identify which is expected to be a stronger acid between the two. So, looking at our given electrostatic potential maps first, for acetic acid, we can see regions of the colors, red, blue, green, yellow and almost a neon blue color. Whereas in our electrostatic potential map of tri fluro acetic acid, we see a largest region being red with a medium range of blue and then a very small amount of our colors, neon blue, green and yellow within this electrostatic map of triflo acetic acid. So based on these visualizations, we're going to recall that for an electrostatic map, our blue regions represent electron poor regions whereas red regions are going to be electron rich. And we want to recall that the most acidic hydrogen is located in the most electron pour region. So looking at our molecule of acetic acid, first, we're going to recall that the carboxyl group represented by Coo H. So again, this is our carbo so group, we're going to recall that within our given molecule, the carboxy group is going to be at the position where we have a carbon bonded to two oxygens, where on one of our oxygens, we have a bond to hydrogen. And we can see this in our electrostatic potential map of acetic acid where the bond between our oxygen and hydrogen. We can see that the hydrogen is located in a blue region. And as we stated, a blue region in our map is considered an electron poor region. We would observe the same pattern in our electrostatic potential map with our molecule of triflo acetic acid where again focusing on our carboxyl group, our bond between our one oxygen and hydrogen. Looking at that hydrogen, it's located in a blue region which is considered electron poor. So we can see that in both acetic acid and tri fluro acetic acid, the hydrogen is located in both blue regions and therefore is the most acidic hydrogen. However, the difference here, as far as determining the most or rather the stronger acid between our two acids, we're going to notice that in our electrostatic potential map of tri fluro acetic acid, as we stated before, the largest region of our map is going to be red, which as we stated is electron rich. And because we have the largest region of this map surrounding our molecule of triflo acetic acid being electron rich, these regions which are red are going to pull electrons more towards them. And we want to recall where we have a stronger pull of electrons, we would have a slightly negative charge. Whereas when we have a weaker pool of electrons, we would have a slightly positive charge. And so where our acidic hydrogen and triflo acetic acid is located, which is in the blue region, we would place a slightly positive charge. And that means that because triflo acetic acid has a large expanse of our red region being electron rich. And we have the dipole that leaves us with a slightly positive charge in our blue region, which is electron pour where our hydrogen, where our acidic hydrogen is located. We would say that triflo acetic acid is the most acidic. And so our final answer is going to be that in both acetic acid and triflo acetic acid, the hydrogen is located in both the blue regions and therefore, is the most acidic hydrogen in our carboxyl group. And we can also state that our triflo acetic acid is the most acidic. And so what's highlighted in yellow corresponds to our final answer? I hope that this made sense and let us know if you have any questions.

Electrostatic potential maps of acetic acid (CH₃CO₂H) and ethyl alcohol (CH₃CH₂OH) are shown. Identify the most acidic hydrogen in each, and tell which of the two is likely to be the stronger acid.

Key Concepts

Acidity and Acidic Protons

Electrostatic Potential Maps

Comparative Acidity

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