I would make my reaction in a Deanstark for the final fischer esterification? I honestly don't know, I'm just doing chemistry on paper I really don't have much lab experience. But what do you think about my proposition?
Ok I see, but from what I see from writing the reaction, is that if I were to do transesterification to from 5 to 6 in acidic conditions, that would be a totally reversible reaction and how could I ensure the formation of the cycle? Since I can't use an excess of reactants right? Unless I...
Hi,
I'm trying to solve the number 5 and 6. Now I'm wondering what happens when I add H2/Pd/C on the 4th (after the question 4) molecule. I know that it will reduce pi bonds to sigma bonds, but will it affect the cetal group? Because if it does't I'm not quite sure that I'll be able to do the...
But if hemiketal turns back to ketone after I add water, and even ifI have alcohol in the solution, i'd no longer be able to turn that ketone into an alcohol no? Because all of my RMgX will be consumed from the moment I add water in the solution? So is it possible to end up with ketones as side...
Hi,
I have a question regarding these 2 possibilities: Why does the addition of RMgX on an ester always form a ketone? We could very well have that tetrahedral intermediate without eliminating the alcoolate group no? Since your reaction pretty much always tend towards the formation of a weaker...
I think for reversible processes the total variation of entropy is equal to zero because dQ = 0. I think it's like pumping your bike in two different ways :
1) You do it very fast, entropy is generated and heat is also generated, and you can feel it by touching your bike pump. This process is...
I'm not quite sure for the name in english but in french it's acide paratoluène sulfonique. The formula is :
H3C-Ph-HSO3.
I also have a question regarding protecting groups. In a molecule where I have both a RCOOH, or ester and amide group, will I be able to use ethylene glycol or Corey Seeback...
Hi, I am trying to solve number 8. At 7, I have a molecule that contains both an amide and ester function. So when I use LiAlH4, will I reduce both the ester to alcohol and the amide to secondary amine? Or just the ester?
Thank you so much for your help!
Hi, I am trying to determine the velocity of the particle with the mass m coming out of the acclerator.
I tried writing :
Ep(i) + Ec(i) = Ep(f) + Ec(f)
Ec(f) = Ec(i) - Ec(f)
But at this step, I'm no longer sure how to express Ep with V because :
In my textbook, it's written :
Ep = 0,5...
I don't understand why in order to make RI from ROH, you'd have to use FINSKELSTEIN condition:
ROH + PBR3 --> RBr
RBr + NaI --> RI + NaBr
and not directly
ROH + PI3 --> RI
Thank you so much for your help!
Pardon me if my english is not correct.
<mentor edit>
Thank you for your answer but I am not quite sure i'd know how to write the mechanism if i start with the ene side. Do i still form a ring of 4 or when i break the pi bond, it would go to the more electronegative oxygen?
Hi, please help me write the mechanism of this reaction. Usually id have an alpha hydrogen for me to do an internal proton transfer, but in this case i don't know what to do. I know the last step is wrong but i don't know how to obtain a carbonyl orcarboxylic acid form this.
Thank you so much...
Hi, I'm I supposed to find an ether with acidic hydrogens or a very strong electrophilic centre? I'm trying with acidic H but it doesn't seem to be working...
Please help me thank you!
Thank you sir! My excuses for my math. They gave the heat capacity of N2 for the following question that asks about the combustion in 20% O2 and 80% N2.
This question is for combustion in 100% O2.
But again, thank you so much for your help!
By the way, I found 2280K for the combustion in 20%...
Hi, I have to calculate the maximum flame temperature of the reaction above. The answer is 4805K but I didn't manage to obtain that answer. Please help me find my error, thank you so much! The values of C are below the solution attempt.
Hi,
I don't understand why this correction would be a nucleophile substitution?
From what understand : The O atoms in the cyclic glucose acts as nucleophiles. ICH3 is also a nucleophile due to the presence of iodine's "non bonding electron pairs" (sorry I don't know the right term for this), and...
Hi,
I have to determine the reaction mechanism of this molecule.
Can someone please explain to me why the reaction would occur on OH (A)?
Is it bc you can't have 2 pi bonds next to each other and OH(A) is the only polarised bond in the molecule where it would easily break off and form a double...
Hi,
Sorry in advance if the vocab is incorrect, I'm translating this from french.
In the correction, it's written that the 4th carbocation is the less stable due to the attracting inductif effect of the carbonyle group.
But isn't this carbocation stabilised by the mesomer effect of the C=O bond...
Hey,
I have this equation in which I have to determine its reaction mechanism.
I managed to determine how we managed to obtain this the molecule in the picture above, but I don't understand the mechanism behind obtaining the second alkene. Thank you so much for your help, and sorry if the...
Hi,
I have to determine which molecule ( 2 and 3) is more stable.
I tried to determine the stability using the inductive effect, but when I tried to that, I ended with molecule 2 being more stable than molecule 3 since:
x3 ch3 will push electrons towards c+
Whilst in the 2nd molecule the is a H...
Ok I see thank you so much for your help. So in case where I'm using I-131 to detect hyperthyroidism by scintigraphy, the sensors should surround the patient completely because gamma photons are emitted in all directions right? And again, sincerely, thank you sir!
What's happening in the diagram is actually what's troubling me. Iodine's nuclei decays into an excited xenon atom. The excited xenom atom emits gamma photons to attain a lower and stable energy state by emitting gamma photons. Therefore the nuclei that emits gamma photons is the excited...
Yes, sorry, I am talking about I-131. But I don't understand how the gamma photon is produced and I can't seem to find an explanation for the origin of the gamma photon emitted by I-131's nucleus. I see how gamma radiation is produced by the excited Xe nucleus, but not by iodine's.
Hi,
I'm struggling to understand an answer in my MCQ.
It states that a scintigraphy would detect γ photons emitted by the iodine's nucleus, and the answer was correct.
But I don't understand how it would detect γ photons from the iodine's nucleus since it disintegrates by forming Xe*, an...
Hi,
I'm struggling to understand an answer in my MCQ.
It states that a scintigraphy would detect γ photons emitted by the iodine's nucleus, and the answer was correct.
But I don't understand how it would detect γ photons from the iodine's nucleus since it disintegrates by forming Xe*, an...
Probably I have, but I'm not quite sure how I would use those formulas for an object in geostationary orbit... and I'm taking physics as a minor so I don't really remember much
Hi,
They gave me this formula T = 2piR / v, with T the revolution period of the satellite, R the distance between the center of masses and v the velocity.
They gave me the value of G and the eath's mass and asked to determine the value of R.
I don't even see fromwhere I should start...
Thank...
Hi, I was given this exercice where I have to calculate the penetration distance, knowing that m = 20g, v = 300km/h and C = 750 N and I have to give the results with two significant numbers. I really thought that all I had to do was replace the values so I did :
d = (20.10^-3) x (300/3,6)^2 /...
I think that the prof doesn't like negative signs, so instead of using the energy released which is going to have a negative value when we consider the system, he just uses the available energy so the energy would be positive. I didn't get the chance to ask him since all classes are uploaded...
I think it's the available energy in an atom with either an excess of neutron or proton depending on the β radioactivity. I'm not quite sure though sorry, it's just what's written in the text that we have to learn...
I'm so sorry for that.
Ed represents the available energy. The formula Ed = [Mn(X) – (Mn(Y) + m(e))] c2 uses the mass of the entire atom and is used for β+ and - reaction.
But when only the mass of the nuclei are given, we end up with two different formulas :
Ed = [M(X) – M (Y)] c2 for β-
Ed...
Hi,
I understood that to calculate the available energy in these two reactions could be calculated from Ed = [Mn(X) – (Mn(Y) + m(e))] c^2, but when I have to change use the atoms' mass instead of the nucleons' mass, it gives out two different formulas :
Ed = [M(X) – M (Y)] c2 for β-
Ed = [M(X)...
Oh ok ok I got that thank you two so much!
For the displacement after 40swouldn't it be 40m?
For the velocity I'm not quite sure.. I really thought that it would be 0 since it's the moment the ball landed..
I think the thing that what's stopping me is that I don't know whether the time an object takes to go up is different from the time it takes to go down..
Because I've been considering that it's different, so i didnt really manage to write the equation..
At 4s, wouldn't the velocity be 0?
If I...
But in this case wouldn't I have to values of gravitational acceleration?
When the object is going up, acceleration is negative and when it goes down, it's positive.
Therefore I couldn't use the 4 seconds value because ( i think ), the time the object takes to go up is different from the time it...
Hi,
I was given this problem saying that a ball is thrown vertically up in the air and returns to its initial position after 4 seconds. The acceleration due to gravity is given to be equal to 10m/s^2.
I tried to attempt this problem by using the equation :
v^2 - v0^2 = 2ah by considering...
No they didn't give out the value of the angle alpha.
That is actually the following question where I have to determine its value, but without acceleration, I can't really finish the exercice.
No i do not know the correct answer. This is a picture of the exercice.
It's just indicated 1:1 ratio. I have zero idea about what is the equivalence of the distance I measured with a ruler. So I just decided to use the distance I measured with a ruler to put in the excel.
And also I'm supposed...
So the initial velocity is equal to 0, and by that you're saying that a = 2 times the value of the slope.
But by doing the excel, I ended up with many slope values.
And when I tried enter the value of a = 0.625 x 2 = 1.25 it was the wrong value.
Do I have to calculate the average of all the...
1. What is the significance of the slope (gradient) of the straight line?
2. What is the significance of the zero time intercept?
Hint: ##x(t)-x_0=v_0t+\dfrac{1}{2}gt^2.##
I was thinking that the value of the gradient would be the acceleration but apparently it wasnt the correct answer. Does...
Yes sorry it was shifted to the left. But I tried to use the value of the slope to determine the acceleration but it was incorrect. And if speed is a straight line, it means that the acceleration is constant no?
Thank you!
I managed to get this graph, and I tried to set Acceleration = Speed(n+1) - Speed n / Time (n+1) - Time (n)
Does this mean that the accelaration is equal to 0.625 m/s^2?
Thank you!