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  1. duchuy

    Which ether solvant must we ban when making grignard reagents?

    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!
  2. duchuy

    Maximum flame temperature during Combustion of CH4

    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.
  3. duchuy

    Chemistry Methylation of glucose (mechanism)

    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...
  4. duchuy

    Chemistry E1 reaction on levosalbutamol

    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...
  5. duchuy

    Chemistry Carbocation stability

    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...
  6. duchuy

    Chemistry Elimination reaction (E2)

    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...
  7. duchuy

    Chemistry Carbocations stability

    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...
  8. duchuy

    Biology Iodine 131 for hyperthyroidism (β- disintegration)

    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...
  9. duchuy

    Iodine 131 β- disintegration

    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...
  10. duchuy

    Altitude of Geostationary Orbit

    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...
  11. duchuy

    Ballistics -- How deep does the bullet penetrate into the wood?

    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 /...
  12. duchuy

    Available energy in β+ and β- nuclear reaction

    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)...
  13. duchuy

    Determine initial velocity of a vertical throw

    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...
  14. duchuy

    Determine the acceleration of a puck on an inclined air hockey table

    Hi, I'm struggling to start this exercice, where I have an inclined air hockey table with an angle alpha. They gave me this chronophotography (this is online) saying that the ratio is 1:1 I really don't know how to proceed since this is online and I'm thinking if I measure this with a ruler...
  15. duchuy

    Magnetic permeability and optical impedance

    Hi, It's given that an electromagnetic wave (5.10^14 Hz) travelling in an environment with the index n = 1,33, where the magnetic permeability (μ) is equal to the magnetic permeability in a vacuum (μ0). The optical impedance (Z) is given by the formula : Z = μ . c/n. I tried to turn μ into μ0...
  16. duchuy

    Wave propation -- Speed variation in different indices

    Hi, I have this question about the variation of wavelength and frequency as light travels to an environment with a different index. As we have learnt in class, celerity can change as light enters a different environment, however frequency and wavelenght are independent and remain constant...
  17. duchuy

    Vectorial additions

    I have this relation that says : vector Ep = vector E1 + vector E2. Given the angle between the vector is equal to 60 deg and E1 = E2, I have to give the relation between Ep and E1. I'm struggling to add the angle value in this, since vector Ep = 2 vector E1. But since this isnt equal to vE1...
  18. duchuy

    Point mechanics -- Tension in a rope from a hanging mass

    Hi, I'm being asked to determine the tension of a rope only knowing that g = 9.8 m.s-2. I understand that in order to calculate tension, I would need to multiply mass with acceleration. But i dont understand how i would in this case. This is the question for reference. Thanks for your help. And...
  19. duchuy

    Waves and propagation

    Hi, I need help finding the phase difference between the two rays converging at F'. I was given this figure, the distance between the lenses is 10cm, the thickness of the lense is 1micrometer and the indexes are on the figure. The light is a laser in which lamda = 500nm. I tried to write down...
  20. duchuy

    Spherical diopter formula

    Hi, I dont understand how the professor managed to determine the values of alpha, alpha' and omega. What is the formula tha´t is applied to determine alpha = SP / AS and so on... knowing that alpha is a really small angle. Cheers
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