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Everything posted by hypervalent_iodine

  1. You’ll have to forgive me for not assuming you were overly aware of the very real horrors of our history after what you posted in the OP. No one is saying it shouldn’t be celebrated, just that it should perhaps be done on a day that doesn’t utterly disrespect Indigenous Australians. Do you think First Nations people should just get over what happened to them because we said sorry in 2008? Should we not reinforce those words with actions with they were sciencerly meant? To me, and to many people, being Australian is (or should be) about being inclusive, welcoming and fair to all people. We don’t achieve that by ignoring our history and the damage colonisation has and continues to cause.
  2. There's a lot of controversy around the date of Australia Day here, which is partly why I responded. It is meant to commemorate the landing of the first fleet, which was on Jan 26, but in doing so it alienates Australia's First Nations people. They call it Invasion day and consider it a day of mourning, since it is the date that coincides with the invasion of their home and murder of their ancestors by white European settlers. There is a push in recent years to have it changed to a different date, which is not unprecedented as it has historically been celebrated on several different dates. Most people don't seem to mind when it's held, which suggests it could easily be changed without much backlash. And why wouldn't you want to? Australia isn't exclusively a country of white people, and it doesn't hurt anyone to change the date to something a little more respectful and kind to our First Nations people. On the other hand, the PM, with the support of many right wing pundits, has decided to double down on Australia Day being when it is, forcing councils to move their citizenship ceremonies to be on Jan 26 and then sinking $6.7mill into making a replica of James Cook's ship, the Endeavour, and having it circumnavigate the country as part of the celebrations (something James Cook never did, by the way).
  3. Oof, what a very white washed and Euro-centric retelling of an extremely brutal history.
  4. It won’t produce any gas AFIK, just calcium hydroxide and then calcium acetate. What’s wrong with just using baking soda and vinegar? You could add dry ice if you wanted a nice smokey effect.
  5. ! Moderator Note Once again, could we please get back on topic.
  6. Yes, those. I am not very familiar with them personally, but it seems like it would be workable for the OP. Thermo literature states that their current model can profile PEG quite well and quantify polyacrylic acid down to ppb levels in industrial cooling water samples.
  7. You can use use a Corona detector in tandem with HPLC, which would circumvent the need for a chromophore. Not sure if that would be cheaper than MS, but you’d need a decent amount of money either way I guess.
  8. It matters if it is a single compound if they want to measure it at ppm levels, as stated in the OP. Thank you for the tutorial in IR that you posted. As it happens, I use IR regularly, albeit for characterisation rather than quantification. In any case, I can’t for the life of me figure out why you have posted it here? It doesn’t refute anything that I have said wrt the suitability of IR for the OP’s stated intention. Moreover, I would like to add that you are unlikely to see alkene stretches in this instance. These peaks are typically very weak, and would likely be obfuscated by OH peaks (if present), and the myriad of other peaks in there that would be there in greater number and thus have much higher absorbance. I have to ask, why exactly are you being so stubborn on this point? You have been told by two people who work in chemistry that IR is not a good option in this instance, for the reasons stated. You stubborn insistence is confusing. I have in fact suggested another alternative, HPLC. You would need a particular type of detector to do it for these samples, but I cannot think of any other way to easily quantify aqueous solutions of PAG. @Mt21 you may also wish to ask your question at Chromatography Forum. It’s reasonably busy and has a lot of talented people there who specialise in quantification and the various pieces of equipment you might come across. I used to frequent there a lot when I worked in an analytical lab as a technician.
  9. I don't think you are understanding what I am saying. PAG is not one compound of a specific chemical formulae; it encompasses many, many possible compounds. IR wouldn't to be able to distinguish between these and as such, you cannot correlate the absorbance of any particular peak to concentration in the same manner as defined by Beer-Lambert, meaning you would not be able to accurately or precisely quantify it. So again, IR is a poor choice and would not suit the OP's needs, regardless of how often they need the testing done.
  10. It's interesting, but it still doesn't help the fact that IR would not be able to differentiate between the different types of PAG present, which would render any effort at quantification unreliable. Not to mention the undoubtedly huge cost of buying a dedicated machine from a company like Bruker.
  11. IR would be a poor choice. As mentioned, the water (a strong IR absorber) would obfuscate the spectra and make quantification very difficult (or impossible), especially if you’re talking about ppm concentrations in swimming pools. I don’t think GCMS is a great choice for a polymer either, as it would be too big and unlikely to run through the column. The other issue is that PAG is not one single compound. You could potentially do it with LC with the right set up and correct detector, but I am not 100% sure on this. This seems to suggest it’s possible, but I didn’t read it thoroughly.
  12. Where exactly do you need help and can you show what you have done so far?
  13. ! Moderator Note I suggest we return to the topic of the OP. If you wish to discuss sexism more broadly, you are welcome to open a new topic.
  14. That would be my guess. I had a look at a few of the accounts yesterday and they seem benign. Sometimes we do have spam accounts that registered years ago suddenly make an appearance, updating their profile with photos and spam links, but this does not seem to be the case here.
  15. ! Moderator Note Welcome to SFN. Please note that this is a discussion forum and as such, threads should be posited with a view for continued dialogue amongst our members. As your OP offers no points for conversation, I am going to close this. You are welcome to post it as a status if you wish.
  16. ! Moderator Note You've been given several chances with this content, and you have been asked not to bring it up again. If you do not stop, you will have your posting privileges revoked.
  17. Could you be more specific? Sulfanmides appears to be a typo, so can I assume you are talking about sulfonamides? If so, sulfonamides are some of the oldest antibiotics that saw widespread use. They went out of favour because of resistance. Of course, the term is very broad, so is there another type of sulfonamide, or other sulfa drug, that you are referring to?
  18. The seal formed for dry vs wet is quite different I think. For brass, another factor is that have your lips lubricated allows you to move your mouth around the mouthpiece easier, which is crucial for several reasons such as creating different sounds / intonations, and hitting higher and lower notes. Couldn’t say if it’s the same for woodwind, but I’ve played brass most of my life.
  19. You are missing so much knowledge required by this question that the only way to really help you here is to give you the answer. That doesn’t help you learn anything, and I personally don’t need to prove that I can complete a first year chemistry assignment. As I said before, the help you need for this is too comprehensive to be reasonably addressed in a forum such as this. You’re just missing too much of the fundamentals. I recommend this site if you’re interested in studying it some more: https://www.chemguide.co.uk/physical/acideqiamenu.html#top You’re welcome to come back if you have questions. If not, I wish you the best. I told you what they represented on the previous page. HA is the general form of an acid (in-tact), and A- is the deprotonated form of the same acid, aka the conjugate base. I was asking you what HA and A- correspond to in your specific question.
  20. As someone who has tutored this subject for 9 years, I can tell you that you aren’t going to get anything useful out of learning something in 20 minutes if you don’t back it up with your own study. Time and time again, the students I saw who continued to do poorly were always the ones who treated sessions as their primary form of study. We are simply trying to figure out what you know and what you don’t, and prompt you in the right direction. If you truly cannot figure out what the acid and conjugate base is in your question, then you are simply not equipped to do this assignment, and you need to (as I mentioned previously) go away and spend time learning and practicing questions related to the module. You are going to spend several hours / days studying this stuff if you want to be able to understand it.
  21. There are not a lot of hard and fast rules with figuring it out. There are some things you should know. Organic acids tend to be weak. Carboxylic acids, for example. Ammonia is a good example of a weak base. Strong acids you encounter most are things like HCl, and H2SO4. Strong bases you encounter at this level are frequently hydroxides, like NaOH. Generally though, whether or not you are dealing with a weak acid or base should be implicit in the question. If they give you a Ka or Kb, it’s fair to assume you’re dealing with a weak acid or base. Similarly, if they give a dissociation reaction using equilibrium arrows, it’s probably a weak acid or base. You can also tell by looking at the equivalence points on titration curves, if given.
  22. You should watch some more of those Kahn academy videos. They are quite good, and will help you in your understanding. You will need to spend some more time getting a better understanding of where all these numbers are coming from and how to use the equations and graphs, otherwise you will struggle when it comes to more complex questions. Based on your previous post, you also need to work on the more basic concepts related to stoicheometry, calculating how much product is formed from reactions, limiting reagent questions, etc. Google will provide you a wealth of resources to learn and practice these concepts from.
  23. Close! You’re mucking up the calculation of concentrations though. In part b., you cannot simply add and subtract the concentration values in the way that you have, particularly since once you add the two volumes together the concentrations change. I would suggest first calculating how many moles you have in the 100 mL of acetic acid and 30 mL of NaOH and rethinking the question with those numbers instead.
  24. Where do you get 0.769 from if you don’t know what the values correspond to? Do you know which species the Ka is in reference to? Remember that if we are using HH, we are talking about a weak acid or base. Can you identify a weak acid and/or base in your question?
  25. I would be wary of posting entire pages of text books. I assume it is covered under copyright laws? If so, you may wish to consider removing them from your posts.
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