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  1. chem_tr

    Decrasing solubility of quaternary ammonium compound in water

    Thank you for your interest.. I do not have the facility to freeze-dry the compound, so I think I will use high vacuum and distill the water to attempt precipitation. By the way, I was away from the lab for some time, and when I returned I saw that a small precipitate formed, maybe due to...
  2. chem_tr

    Ammonium help

    In aqueous solutions, two types of reaction may occur: 1) Since ammonia is a base, copper hydroxide my precipitate. 2) excess ammonia can give a complex with copper. Please skim your textbooks once again by referring to my clues.
  3. chem_tr

    Decrasing solubility of quaternary ammonium compound in water

    Hello, I have synthesized a compound with two quaternary ammonium groups and two cyanide groups. I did the reaction in dmf, and after the reaction I poured the reaction medium onto ice-cold water. A little precipitate formed, but I think this is not the compound I want, my compound is still...
  4. chem_tr

    Phenol acidity

    I agree. If you are seeking extremes, you might want to add sodium hydride (a very strong base, not needed to prepare phenolate) instead of the commonly used sodium or potassium hydroxide in tetrahydrofuran under 10°C in a controlled manner.
  5. chem_tr

    Feso4 is not a primary standard?

    Hi It cannot be a primary standard. Because it is not stable. A primary standard must be cheap, inert (stable), etc... You may want to do a google search about "primary standards".
  6. chem_tr

    Basicity of NaSH compared to NaOH?

    Hi I think it is less basic than NaOH, since the acidic adduct of NaSH is H2S, where NaOH produces H2O. Since the former product is more acidic, the parent compound (NaSH) must be less basic. Regards
  7. chem_tr

    What is with all the homework question in the chem forum?

    The new forum policy is acceptable, I think the moderators and administrators are seeking more scientific topics discussed right here, other general and strictly homework-related topics are wanted to be posted in another parts of this forum.
  8. chem_tr

    Ahhh! Titanium Chloride

    Yeah, radicalic hydrogen is the best. Isn't sodium borohydride alone (in dilute alcoholic solution, for example) is sufficient in reduction? You might cool the solution to say, 0°C, to reduce its vigorous nature, and quench it with diluted HCl after slowly bringing the medium to room...
  9. chem_tr

    Chemically dissolve aluminum?

    Well, I wonder if you try a redox reaction, such as placing electrodes and using an electrolyte such as aqueous acid solution; with this way you might dissolve it as Al3+ ions and not give harm to the coating. However, it would be wise if you make a little hole inside the wall of the tube, so...
  10. chem_tr

    Has anyone heard of P and M notation?

    Thank you very much. I constantly learn a great deal of knowledge from you. It is very good thing to have you here. To tritertbutoxy: As I understood from Movies' message, it works similar to CIP system; but with one exception: This system is used in chiral molecules with no asymmetric atom...
  11. chem_tr

    Nucleophilicity of Acetylide ion

    Hello, It is possibly because of the fact that pi system in vinyl and extended pi system in acetylide causes the basicity to be lower than that of methyl. Pi bonds tend to love electron pairs, so basicity is lowered. However, please let me inform you that nucleophility is not the same...
  12. chem_tr

    Has anyone heard of P and M notation?

    Has anyone heard of P and M notation? Hello, A friend of mine has asked a question about a molecule, we think the molecule was a biphenyl molecule with two nitro groups on each benzo unit, along with two carboxylic acid moieties on each ring. So the molecule was shown to be in two isomers as...
  13. chem_tr

    IUPAC Nomenclature

    Have you tried examining through the sticky thread on Chemistry forum? I think you will find suitable website there.
  14. chem_tr

    Lewis Structures

    Hello, In case you cannot find your Lewis structures in the site, let me instruct you some basic knowledge. a) Find the neutral valence electron counts of the atoms, and find the total number of valence electrons. In case of negatively charged ions, this value will probably is an odd...
  15. chem_tr

    Interfacing a PC to a UV spectrophotometer

    Thank you, I guess the code includes one "stop bit", one or two "init code", etc. If so, I have a documentation of the old printer mentioning these. Is it possible to use the same settings for the computer?
  16. chem_tr

    Blue lake test .HELP

    Maybe you need to review what's been happening in the experiment. You add litmus, whose color is blue in alkaline solutions. It is possible that the concentration of HCl is too low to provide required acidity, but ammonia solution is more concentrated than HCl to yield a basic solution...
  17. chem_tr

    Interfacing a PC to a UV spectrophotometer

    Hello, We have an old spectrophotometer which contains an outlet saying "printer/computer", and until now a dot-matrix printer has been attached to it. However, the printer is no longer functional, and I am thinking of interfacing an old PC to the spectrometer. The printer was attached via...
  18. chem_tr

    Boric Acid Esters

    I have done this reaction with borax, Na2B4O7.11H2O with sulfuric acid and methanol. I got a nice green color, since sulfuric acid destroys the mineral to give free boric acid, B(OH)3, and also shifts the reaction to the ester side. Hope this observation helps too.
  19. chem_tr

    Copper Ion Flame Test

    I think you have done a redox reaction. Because chlorate and sugar in the presence of copper(II) ions tend to react with each other. The intensified bluish color may be the result of this redox reaction, along with exothermic nature of the reaction; it might raise the temperature to turn your...
  20. chem_tr

    Problem with round bottomed flask

    My offer is very simple; just take a wooden object (tube holder, etc.) and hit the joint very gently and patiently. It will budge after some time. You may accelerate this by applying some grease on the joint and heating. My approach works especially with stuck caps.
  21. chem_tr

    Help on 19F-NMR

    This helped a lot, more than you'd imagine. Thank you.
  22. chem_tr

    Help on 19F-NMR

    Hello, A friend of mine has synthesized a compound with pentafluorophenyl groups, and is willing to characterize it via an additional 19F-NMR. However, the person responsible for recording NMR spectra is inexperienced in 19F-NMR, so we need help on recording the spectra. We have...
  23. chem_tr

    About Williamson ether synthesis

    A last question: Is there any danger of self-reaction for 2-bromoethanol? What must I do to avoid this? I mean, when I add 2-bromoethanol into the sodium salt of my alcohol, I want that the alcoholate attacks 2-bromoethanol but not else. Shall I react 2-bromoethanol with sodium ethylate to...
  24. chem_tr

    About Williamson ether synthesis

    Thank you very much! May I learn your comments about my second question? Will I be able to obtain a better solubility in common organic solvents after alkylation with BrCH2CH2OH or ClCH2COOH (this one will be water-soluble, I think)?
  25. chem_tr

    Thin Lead Chromatography help

    I see. I will not use a flash column, mine will be a simple and short column at ambient conditions.
  26. chem_tr

    About Williamson ether synthesis

    I am planning to perform some Williamson synthesis. However, I have not been successful on obtaining a literature with described procedure. Will I need any procedures? I have looked at Organic Syntheses website (website url), but no procedures on the Williamson's technique. My plan is simple...
  27. chem_tr

    Thin Lead Chromatography help

    I will try my best, thank you. PS: What is the result if MeOH starts to dissolve some silica gel? I have not seen any "holes" on TLC plate.
  28. chem_tr

    Thin Lead Chromatography help

    Hello everyone, I was poor on TLC before, and am poor now :smile: I want to ask a question to you guys. Please look at the attached zip file with a tif image. My question is very simple: Is it possible to fully isolate the impurities (yellow spot and light olive-mustard-colored...
  29. chem_tr

    Undo Highlighters Chemical

    Well, this is an insufficient question, I suppose. Yellowish light can be absorbed by viewing from a blue glass (cobalt glass, as we call it), but the process is purely physical. The chemistry is in synthesizing or employing the blue chemical on the highlighter. Since the question is incomplete...
  30. chem_tr

    Am I getting the correct answers for these Chemical Equilbium (I have a test tommorow

    I got 2.2 and 1.2 moles for P4 and H2, resp. 0.4 and 2.4 moles are really present, but they are reacting amounts of them, so you will subtract these from the beginning amounts, i.e., 2.6 and 3.6 moles, resp. I don't have enough time to look at the remaining questions, sorry.
  31. chem_tr

    Am I doing these Chemical Equilibrium Mass Action Expression problems correctly?

    Your first reaction includes the following conditions, if I understood correctly (the volume is constant and 0.5 L): a) 2.5 moles of SO2 vs. 1.0 mole of O2 b) 0.5 moles of O2 is used c) 1.5 moles of O2 is excess in the medium (equilibrium is established) If the reaction is like below...
  32. chem_tr

    Am I doing these Chemical Equilibrium Mass Action Expression problems correctly?

    My help will not be about solving your problems, you don't seem to show your brainstorming here. Subscripts are done in two ways in PF. First way is using BBCode technique. In here, use {sub} and {/sub} to indicate a subscripts, like this: H{sub}2{/sub}O. The only error I made intentionally...
  33. chem_tr

    Gokul43201 gets Promoted!

    Congratulations, Gokul! I have been away for too much, but it is very pleasing to see you earn this great prize you have deserved for a long time.
  34. chem_tr

    Problem related to Alkenes

    Well, 2-butene has two same carbanion intermediate, either H_3C-CH^--CH^+-CH_3 or H_3C-CH^+-CH^--CH_3. In each case, the result does not change; the product will contain Cl^- where the CH^+ lies, and H^+ at the position of CH^-. The case for 1-butene is different. Here, two kinds of carbanion...
  35. chem_tr

    Organic Chemistry: Haloform Reaction

    Haloform test is ideally positive for methyl ketones; the C=O group attached to a methyl group increases the overall acidity of methyl protons due to tautomerization to enol form. So the X you wrote should be a strong electron withdrawing substituent, or at least a group with a highly...
  36. chem_tr

    A hard electrochemistry question (in my opinion)

    Thank you, I haven't remembered that one Ampere is equal to one Coulomb per second, so I was stuck. Again, thank you for your help.
  37. chem_tr

    A hard electrochemistry question (in my opinion)

    Dear Borek, you said one Ampere is one coulomb per second. Then 1,000 amperes are equal to 1,000 coulombs per second. This in turn gives 6.25*1021 electrons per second, which means about 0.01 moles of electrons per second. In the redox, two electrons are used as you stated; so 0.005 moles of...
  38. chem_tr

    A hard electrochemistry question (in my opinion)

    I know this. One faraday constant is equal to one mole of electrons - this is equal to 6.023 \times 10^{23} \times 1.6\times 10^{-19} = 96368 \frac {Coulomb}{mol}
  39. chem_tr

    A hard electrochemistry question (in my opinion)

    Hello all, As I am preparing for my PhD proficiency exam, I tried to solve some Analytical chemistry problems. and stuck in one. Well, I have attempted to solve this, but have not found enough evidence to study on and solve the problem. What I've done is basicly the following: I am in...
  40. chem_tr

    A quick chemistry Question

    Well, I am not sure about so-physics-related-chemistry issues, but look for Balmer, Lyman, Paschen, or Pfund series, characteristic for hydrogen atom. These show clearly that there is a quantized behavior in hydrogen atom. The same approach in other atoms are rather complicated due to...
  41. chem_tr

    A quick chemistry Question

    What have you studied? Please show us some of your attempts of your brainstorming. Frequently, you have the traces of the answer in your mind, and only you'll do is to gather them.
  42. chem_tr

    When they combine

    They will not combine-they will be attracted to each one, but repelled after some degree. Let's say Na+ ion's outer shell of electrons repel the ones belonging to Cl-. This is the most simple approach, but enough for a start. However, positron and electron does not behave like this, their...
  43. chem_tr

    A question about calorimetry

    Oookay, so I have made the error of not considering the total volume as Bystander suggested; my logic doesn't seem so wrong. Thank you all!
  44. chem_tr

    A question about calorimetry

    I haven't found my textbooks on physical chemistry, so I want to ask the forum members. When we heat 4 liters of water from 10°C to 90°C, and add this to 16 liters of water at 10°C, what will the final temperature be? My brainstorming revealed the following, but I'm not sure if they are...
  45. chem_tr

    Question about AMU & Temp. Conversions

    Hello Your first question is about carbon's 12-based amu system. If you look for carbon, you'll see that it is 12.00 amu, where its previous partner, oxygen, is 15.999 (formerly it was used as a standard to be 16.00). English is not my native language, so I don't know how to pronounce it...
  46. chem_tr

    Why sometimes is it more accurate to weigh liquids than to use a graduated cylinder t

    Yes, this is correct. If you first weigh a clean and empty glassware and zero it while it is on the balance, and then add a required amount of liquid (considering its density), you can calculate its volume. Some analytical balances can weigh accurately to 0.01 mg, and even more.
  47. chem_tr

    Vapor Density: 1.3

    Vapor density of 1.3 means, in my opinion, that this solution has 1.3 times more of that molecule in the gas phase than the solution in the equilibrium.
  48. chem_tr

    10,000ppm hypochlorite

    If your concentration (12%) is 12 grams of solute in 100 mL of solution, then we know the density. From there, you'll find the concentration as 1.2x105 ppm if you recalculate. Appropriate dilution will give you what you need.
  49. chem_tr

    10,000ppm hypochlorite

    Yes, you should consider its density to calculate the final mass, from there add the required amount (10.00 mg) to fill up a one liter of solution, which will give you a 10.00 ppm solution.
  50. chem_tr

    What's the blue/black crap in the water? (electrolysis)

    I am not sure, but if the salt has some iodide in it, it might have been oxidized to elemental iodine. You don't seem to do anything wrong. You can filter the solution after you finish the oxidation, and evaporate the solution to dryness.
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