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Posts posted by exchemist

  1. 40 minutes ago, Eed said:

    I've heard that antibacterial soap is no better than ordinary soap. Can someone please explain how ordinary liquid hand soap works? Does it simply help take off debris, or does it break the cells of bacteria and viruses and therefore render them harmless (kill them)?  For example, if someone washed their hands with liquid hand soap but let's just say they didn't wash all of the physical debris off, are the germs left on their hands still considered to be harmful? Thanks

    Soap, being a surfactant, tends to disrupt the bi-lipid membranes which form the cell walls of bacteria and the viral envelope. So yes it breaks them open.  So far as I know, there is no special property of liquid hand soap as opposed to other kinds of soap. Soap in general works this way. Clearly though, it is best to rinse off whatever is dislodged from the surface of your hands.  

  2. I can't immediately see what makes this project fundamentally different from the other inertial confinement fusion systems that have already existed for a number of years. It's certainly not a new idea at all to blast pellets of fuel with lasers, instead of confining  the plasma magnetically in a tokamak.

    Is it the use of boron that is new? 

    It looks to me as if there is a good dose of hype in this article. 

  3. 1 hour ago, Dhamnekar Win,odd said:



     I am working on question (d) for answering it. Any chemistry help will be accepted. Do you know the correct answer for question(d)? 

    You've got in a slight muddle with your equation and the equilibrium constant derived from it. What you have been given is the equilibrium constant for the reaction you were given, not the new one you incorrectly generated on the basis of molecular iodine. You do not have molecular iodine here. You have iodide ions in solution. To balance the reaction there will be some cation, e.g. K+, which does not participate but features on both sides. Apart from the fact that the charges don't balance in the reaction you generated, you can't take an an equilibrium constant you have been given for one reaction and start applying it to a different reaction!  

    I think that, as a result, you have ended up with a factor of 4 in the numerator that should not be there. I did it without that factor and got 2 roots to the quadratic, one of which is 0.38 (the other being 0.73 which is clearly nonsense in this context). 

    With a bit of luck once you have resolved this the rest will come out. 


  4. 1 hour ago, Techgeek121 said:

    My old model car was'nt charging battery enough, first i thought it may be battery issue. but i recently replaced my battery with a new one so there are lesser chances of it. i first check online reasons behind no charging of car batteries and found that it may be due to alternator which may be not charging the battery. So i test alternator of my car, i wana know which is valid method of alternator testing?


    I found a blog on this  https://www.scienceforums.net/topic/126940-how-to-test-battery-of-a-vehicle/


    One thing you can try is, when it is dark, get the car to face a wall, turn on the headlights with the engine off and then start the engine and rev it a bit, to 1500rpm or so. You should find the brightness when the engine is off is the same or a bit less than when the engine is running at 1500rpm. If the brightness is less with the engine running than when it is off then your alternator is not charging properly.

    But a voltmeter would be best. When the engine is running at 1500rpm the voltage across the battery terminals should be slightly greater than when the engine is off. If it isn't then the alternator is not working properly. (N.B. Do not be tempted to disconnect the battery terminals with the engine running, as the battery smoothes the voltage produced by the alternator. You can bugger up any electronics on the car due to spikes in voltage if you are not careful.) 

  5. 3 hours ago, arlesterc said:



    At about 4:53 in this  video -  https://www.youtube.com/watch?v=-QdtwRJdVsM there is a map of the world with major haplogroups.  A lot of Europe and Middle East is in red.  Africa is mostly green.  However there is an island of red a little above the middle of Africa and a little west of center surrounded entirely by green. 
    What is that area?  Which countries and peoples belong in that chunk? 
    What is the connection between that chunk and the red areas in Europe and the mid-east? 
    What are the actual haplogroups, haplotypes represented in the red chunk?
    Any time taken to respond is appreciated in advance.
    P.S. I did post the author on Youtube but did not hear back so I posted here.

    The red area seems to be around the borders of Northern Nigeria, Niger and Chad. In terms of modern culture, I think this more or less where the Christian areas change to Muslim areas, as one goes North, but I don't know what peoples they actually are.

    (As usual I find the video tedious and a poor source of information: I'd far rather read something about this in print.)  

  6. 21 minutes ago, joigus said:

    Silly me. You're right. So the total mass is constant? I didn't see that in the initial statement. By,

    "How many moles of sulfur dioxide must be forced into the reaction vessel", I understood new moles of sulfur dioxide are added to the equilibrium. From what you say, the new SO3 must come from the pre-existing equilibrium, right?

    I had difficulties implying that from the statement. Sorry if I sound obtuse.

    No, there is 1 mole of new SO2 added. But that will put the system out of equilibrium, so more SO3 will form, consuming some of the oxygen as it does so.  As you say, it's Le Chatelier's principle (the chemist's version of Lenz's Law 😀 ).

  7. 35 minutes ago, joigus said:

    Oh, I see; all of them are necessarily gases.

    The bit I don't understand is, what assumption from the exercise's statement is at the basis of O2 going down from 0.2 mol/L to 0.2-0.05 = 0.15 mol/L when the extra SO2 is put there?

    I seem to be missing something here...

    Yes all three are gases. If the SO3 in this 10l vessel increases from 15moles to 16 moles, one mole of O, that is, half a mole of O2, must be consumed. So on a mol/l basis, 0.05mol/l is consumed, isn't it?  

  8. 31 minutes ago, joigus said:

    Flawless application of Le Chatelier's principle.

    I've no objection to there being good practical reasons to remove oxygen, and I totally trust @exchemist with this. But, why do you assume oxygen reducing its concentration --as per the exercise's statement? Are you re-calculating concentrations due to total volumes changing? Can you specify the whole chemical reaction equation with the phases?

    I'm just curious.

    I by no means exclude the possibility I may get problems like wrong, but my understanding of the scenario from the description is you have a number of moles of O2, SO2 and SO3 at equilibrium in this fixed volume vessel, and then you shove in some more SO2, thereby causing a bit more SO3 to form as equilibrium is re-established.....which will inevitably absorb a bit of O2 as it does so. 

    The volume is fixed so it is the pressures that will alter as more gas is added, but it is all expressed in moles, so you can work with concentration in moles/litre, rather than pressures - though it comes to the same thing as long as you have close to ideal gas behaviour.  

  9. 58 minutes ago, Genady said:

    I don't think the pressure disappears. It rather stops increasing after some density is achieved. So after that you can keep compressing it without pushing any harder.

    OK, so that would equate to pushing a progressively increasing proportion of photons into a condensate phase, rather than suddenly reaching a threshold, like a lambda point, at which a bulk transition of the whole system occurs, into a condensate phase.

    However from the phrasing in the description I'm left wondering which of the two it is.  I see that, rather than compressing the photons into a smaller space, what they did was add more photons, increasing the density that way instead. The suggestion is that the compressibility suddenly dropped, as if a lambda point was reached at a certain density.

  10. 8 hours ago, swansont said:

    You can’t separate the photons from the interaction with the mirrors. If you have a photon in a cavity, there is a 2p momentum exerted on reflection, which happens in some time t. As the cavity gets smaller, you reflect more often, so t gets smaller and the force goes up. You have to push harder to compress it.

    That makes sense, but in that case why does the radiation pressure almost disappear as the Bose-Einstein condensate forms? Are we saying the photons all fall into a particle-in-a-box ground state, in which they have only zero point momentum, or something? So, paradoxically, compression "cools" them?



  11. 17 minutes ago, Dhamnekar Win,odd said:

     Yes, I forgot to square the concentration of SO3 in the numerator and the concentration of SO2  in the denominator of the fraction in (b). But R.H.S. 125 is correctly computed.



     But what is your opinion about my answer to (c)?   

    Your logic looks right to me, certainly (well done for allowing for the decrease in free oxygen), though I don't pretend to do this sort of thing every day. You probably have a lot more practice at doing problems like this than I do.  

    I seem to recall you have asked for confirmation of your answers before and they were OK then.  I have a feeling you may be quite good at this - unless I'm mixing you up with someone else.  

  12. 2 hours ago, Mark Corbett said:

    I have actually read the paper. I agree that the paper is more cautious in its claims than the press release from the University and from the news articles that followed. The news articles did make it sound like the experiment had discovered a self-replicating RNA. Here are two examples:

    "According to SciTechDaily.com, the first RNA molecule that can replicate itself was created, thanks to scientists from the University of Tokyo."

    Source:   https://www.healththoroughfare.com/science/scientists-create-the-first-rna-molecule-that-replicates/45320



    "AN RNA molecule that can self-replicate, change its form and develop complexity - or, in other words, evolve - has been developed by researchers for the first time in a discovery that could shine a light on how life first emerged."


    from:  https://www.express.co.uk/news/science/1582670/origins-of-life-breakthrough-evolving-rna-molecule-created-first-time-tokyo

    I trust, then, that your video makes clear the paper is not claiming to have solved the riddle of how the first replicator arose.

    Leaving aside the silly hype in sections of the lay press, do you have anything to say about the content of the paper? 

  13. 10 hours ago, Mark Corbett said:

    The paper claims that the experiment demonstrates evolution. But evolution is not possible, even in theory, if there is no self-replication. So self-replication is a foundational issue.

    Yes of course replication is essential for evolution. However the purpose of this research was not to demonstrate the development of self-replication, nor does it claim any such thing. The title is: "Evolutionary transition from a single RNA replicator to a multiple replicator network". The paper does demonstrate that. 

    Have you actually read the paper? 



  14. 1 minute ago, Mark Corbett said:

    Try discussing some of the science that is related to the topic and we can find out.
    Example: Do you agree that the experiment in question succeeded in producing a molecule or system of molecules that self-replicated?

    That's a bit silly, frankly. As both you and I have pointed out, that is not what the paper is about. It's just a typical pop-sci headline: eye-catching but misleading. So why waste time on that? 

    It would be far more interesting if you can build on my brief summary of what it seemed to me the paper actually is about, as per post 2.  


  15. 2 hours ago, Jakerm1995 said:

    Hey, apologies yet again for the delay. I've had a friend moving in and also one staying with me. Little time to focus on my studies, which isn't good really considering my deadlines. This piece is due in tonight, so I am really going to focus now and get it done. That explanation fits yes, so I appreciate your help a lot. I may need some additional help on the maths side of things, if I ever meet you, I owe you beers for all the help! 

    Well it's 2235 in London, now and I'm tired after a 2hr choir rehearsal (performing Haydn's Creation on Saturday) so I'm off to bed. I think you've got the idea by the look of it now, so hope you manage to work the rest  of it out. 

  16. 17 minutes ago, Mark Corbett said:

    I feel that the news reports on this experiment are misleading.

    The experiment did not produce any self-replication. The replication involved required the use of a whole translation system that was made by living bacterial cell and then taken out of the cell. The translation system itself was not replicated in the experiment, but performed vital steps in the replication process for the RNA. I explain more about this in this YouTube video. Note: the provocative title was inspired by a statement made famous by Mark Twain: "There are three kinds of lies: lies, damned lies, and statistics." However, I think it is unlikely that the authors of the science reports were intentionally lying. I do think their reports include misleading and false statements.


    In post 2 of this thread I made the same  point and provided both a link to the paper and a synopsis of the research, last Tuesday.

    All without making a video, too! 😀

  17. 7 hours ago, jameskennymatheson said:

    Ok so its come to my attention there will be another ice age if we don't figure out how to make salt from air or some other substance the sun heats up to make heat

    The reason we have heat is the sun is using salt water as fuel

    I hope we solve this

    Very serious questions

    For very serious people

    You seem to be another one whose hovercraft is full of eels. 

  18. 24 minutes ago, Jakerm1995 said:

    Sorry again, busy days atm :'D Thanks again for all the help! The water will enter the worms cells through the skin and, thus, the worm will get bigger? Sorry if that sounds stupid ahah

    Yes. And if, like an earthworm, it does not have very elastic skin, it will go pop eventually. But apparently (I did not know this) ragworms have elastic skin and can stretch without being damaged. Also it seems they can tolerate quite a significant dilution of their body fluids and still function. 

    Does that explanation fit the data you have been given?


  19. Here's the paper: https://www.nature.com/articles/s41467-022-29113-x

    Seems the researchers started off with a strand of RNA that included the code for a replicase, i.e. an enzyme enabling it to replicate from nutrients supplied. So it was already self-replicating when they started. Thus, self-replication was not something acquired during the experiment, so that part of the puzzle of abiogenesis is not addressed.

    What was interesting is that during the course of the experiment, different lineages of RNA appeared, due to mutations during the replication process. These competed with one another in a Darwinian manner and eventually several "won" and became established as the main successful types. However something else also happened, which is that some cooperation developed between them. In some cases the replicase code became lost due to mutation, but then RNA lacking this code still could reproduce, by using the replicase created by other strands which still retained this capability. So the final ecosystem of RNA was more subtle than might have been expected.

    At least, that is how I read it, skimming rather quickly. 


  20. 3 hours ago, Jakerm1995 said:

    Hey, sorry for the delay. So to answer your question, I assume that it's just that water will pass through to the more concentrated solution from the weaker one? 

    Exactly. Water will flow to the more concentrated side from the more dilute side.

    So if the membrane is the skin of a worm, and the ionic strength on the inside is approximately that of seawater, what will happen to the worm if it is placed in a solution with lower ion concentration? 

  21. 9 hours ago, Jakerm1995 said:

    It's just the salinity. I have posted a picture of the different seawater treatment concentrations, so you can sort of understand what I mean :'D I hope this helps. Thanks again for your help! :)


    As for your earthworm comment, what do you mean by burst earthworms? Sorry for all my stupid questions 😅

    Aha, so it's seawater equivalent , i.e. in ionic strength, not real seawater.

    Regarding the burst earthworms - and your expanding ragworms - If you have a more concentrated solution and a weaker one, either side of a membrane that allows water molecules to pass through, but not the ions,  what tends to happen? 


  22. 9 minutes ago, Jakerm1995 said:

    125% Seawater* Sorry typo :D I can't seem to edit it. Btw I am still yet to complete those calculations so I apologise for not following up your replies. 

    How can you have 125% seawater? 

    But, to give you a clue about what may be going on, it is common to see burst earthworms after heavy rain. Why do you think that might be?  


  23. 1 hour ago, Jakerm1995 said:

    To provide some context for this question:

    I have 4 seawater treatments at different salinities. At 50% seawater there was a 51% increase in weight over a one hour period. At 75% seawater there was a 26.9% increase in weight over 1hr. 100% seawater = 6.18% increase over 1hr. Finally at 125% water, there was a 7.25% decrease in weight over 1hr. I understand this has to do with osmolarity. The species in question are euryhaline osmoconformers, I have a very vague idea, but would very much appreciate some assistance in understanding what is happening here 😅 

    Any help is welcomed and appreciated! Thanks for taking the time to read this post.

    What does 125% water mean? 

  24. 1 hour ago, harlock said:

    I think some energy needs to be stored first of all. Energy can be stored by melting some salt...or by storing water under pressure in an insulated tank... For example I know that NaCl heat of fusion value is around 30 kj/mol ( 300 kwh/m3! ) so 1 m3 of NaCl can store 300 kwh of thermal energy. But it's a high fusion temp for straw combustion...  

    Think what you are now proposing: to add an energy storage system, as well all the other stuff I have itemised. If you are going to do all that you might as well run a static EC engine somewhere, convert the energy to a convenient form and put that in your on-board storage system.  In short, run a generator and store the energy electrically in a battery. 

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