exchemist

Any argument that concludes no=yes is self-evidently wrong, so the only value in it [yawn] is trying to spot the error. Apart from anything else, if you argue no=yes, you will have the Me Too movement down on you like a tonload of bricks, and quite rightly.

By not requiring everyone to own one, for a start. It's grossly inefficient use of resources, when you think about it. I think that driverless cars, that you summon when you need one, would be a far more efficient system.

Aha. Good to see you run up the Jolly Roger at last: now we know what we are dealing with. Quantum Mechanics is a "construct" in the same sense as Newton's Laws. All theories are constructs, in that they extrapolate from observations to make general inferences - which are then tested against further observation. It is not "blind faith", because these theories are based on observation and tested against observation. So we know they work. That is the polar opposite of "blind faith". You appear to be attacking something here, without first taking the trouble to try to understand it. Is this wise? And, if you think such "constructs" can't tell us anything, I'll be intrigued to see you put forward a theory that is not a "construct" in this sense.

Are you trying to provide evidence for the proposition that philosophy is a waste of time? 😁

Oh really? I think it is because he is scared.

There is also some bleaching effect from sunlight, which can help remove stains that the detergent does not quite deal with 100%. I've observed this with white table napkins, for example. So there could be a bit of an old wive's tale about this, due to the superficial appearance of cleanliness due to UV bleaching.

© Rex Tillerson 2017 😃

Yes, there are well understood reasons for why these energy states are what they are. This is what Quantum Mechanics tells us. QM also tells us how it is that electrons moving between states, or molecules moving between vibration or rotation states, or whatever it may be, can emit (and absorb) EM radiation. This was all sorted out in the 1920s and 1930s, actually, when QM was being originally developed. So it has been widely known for about a century and is taught to all physics and chemistry undergraduates - and even in simplified form in schools, in the 6th form. You really need to read a bit about this before coming forward with ideas of your own. Otherwise you risk trying to reinvent the wheel, from a position of ignorance, which is obviously going to be asking for trouble.

I'm not entirely sure what you are really asking. It's probably a language issue. I doubt that you are being asked for the full algebraic expression for these wavefunctions. It seems more likely that you are being asked to show how linear combinations of appropriately chosen atomic orbitals generate the hybridised ones. This link shows you how 4 sp3 hybrid orbitals can be constructed from s and 3 p orbitals: https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Map%3A_Inorganic_Chemistry_(Housecroft)/05%3A_Bonding_in_polyatomic_molecules/5.2%3A_Valence_Bond_Theory_-_Hybridization_of_Atomic_Orbitals/5.2D%3A_sp3_Hybridization You can do something analogous for the others. By all means come back if I have misunderstood.

The thing you need to keep in mind is that light is always emitted by a source. The wavelength (frequency) is determined by the source that emits it. For example the famous sodium D lines, which make street lamps yellow, are due to sodium atoms emitting a pair of frequencies in the yellow region of the spectrum because the emission is due to electrons in sodium atoms dropping from a pair of levels in the atom to the ground state. But if you look at the tungsten filament in a lightbulb, that emits a continuous spectrum, because this is due to radiation due to thermal motion, rather than transitions between specific energy levels in the atom. Alternatively a radio antenna emits radiation of far longer wavelength (lower frequency), corresponding to the frequency of the oscillation of electrons in the antenna. So it's all to do with the source of the light.

I assume that would be the value FOB. On a CIF basis the value would be considerably less. I wonder if it would even have any +ve value after shipment cost is factored in.

No, this would be a waste of money, for the reasons others have given. For towels in particular, so long as they are hung up where they can dry after use, they will generally last for a week before they need a wash, if only used by one person. After all, people dry themselves with them when they are already clean, right? So they don't pick up contamination very quickly. But if they are allowed to stay damp they will start to smell after just a day or two. Modern hotels do not change towels every day any more, because of the waste and environmental impact. They nearly all ask the guest to put the towel in the bath if really they need a fresh one, and otherwise ask you to keep using the same one. As others have pointed out, there is no need to sterilise clothes or towels. Your body is designed to cope with ordinary domestic micro-organisms without trouble.

Washing soda will have some ability to saponify fats, whereas soap simply emulsifies them. Strong alkalis are often useful in the kitchen at cleaning fats that have degraded and become sticky and resistant to detergents. Oven cleaners are a good example. I'm not sure of the chemistry of these degraded fats (maybe someone else here will know), but it seems that alkalis can still saponify them. Washing soda is not as strong as caustic soda for that (and by the same token is considerably safer to use), but probably quite a bit better than bicarbonate, I would think.

If you heat NaHCO3 to 200C you will indeed decompose it to Na2CO3: 2 NaHCO3 -> Na2CO3 + H2O + CO2. You have effectively been making ordinary washing soda by a rather wasteful and expensive route. Since washing soda will do a better job than baking soda (sodium bicarbonate), why not just buy that instead?

I'm a little confused by this discussion. I always thought that washing soda was Na2CO3, sodium carbonate, rather than NaHCO3, sodium bicarbonate. That would be a stronger alkali than bicarbonate and presumably more effective at reacting with fatty acids or even saponifying fatty material.

Well, cookery being a messy process, scientifically speaking, there will a mixture of solids dissolving, the forming of suspensions of solids in liquid as fine particles, and also emulsions of fatty phase liquid in aqueous liquid. But the mechanical action @Externetmentions may also play a role in initially detaching the material from the surface of the pan.

Not sure if the poster will be back, but my bet is this is an aldol condensation.

Yes, I'm sure that works. Possibly the rapid contraction of the surface may loosen whatever is stuck to it as well. However my understanding, as far as cookery is concerned, is a somewhat less violent process, often done after hot fat has been poured off, with the result that the pan is not far above 100C. Supplementary heating may have to be applied to make the deglazing liquid come to the boil. There is a description here, which fits my experience: https://www.thekitchn.com/how-to-deglaze-10807

No, that sounds wrong to me. In cookery, deglazing a pan is the process of dissolving deposits from frying, roasting etc., generally with wine or vinegar best, to form the basis of a sauce or gravy. Nothing to do with kinetic energy. I do this regularly myself when I am cooking. (In the context of diesel engine cylinder liners, deglazing involves renewing the cross-hatched honing pattern on the liners which retains the oil film, by carefully controlled mechanical abrasion. But that is nothing to do with pans or proteins.)

I'm sure you can find information about HBr and HI. There is a more detailed comparison of the relative strength of acidity of the hydrogen halides here: https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Modules_and_Websites_(Inorganic_Chemistry)/Descriptive_Chemistry/Elements_Organized_by_Block/2_p-Block_Elements/Group_17%3A_The_Halogens/1Group_17%3A_General_Reactions/The_Acidity_of_the_Hydrogen_Halides A lot of this is taken up with explaining why HF is a weak acid, due to the special effects of hydrogen bonding, which is lost when it ionises, and the negative entropy change on solvation. So there is an argument for treating HF as the odd one out. But you will also find a table of pKa values comparing HF, HCl, HBr and HI which indeed increase as you go down the group. (P.S. In spite of being only a weak acid, HF is highly dangerous as it burns skin and flesh and can penetrate down to the bone, causing serious damage.)

If you count the atoms in the product, what has been lost, compared to those in the two reactants?

This looks like homework. What do you think, first?

But the vapour pressure would be less than atmospheric, until it is at boiling point. So it would be incapable of pushing ice out of the tube, surely?

Sort of. There's just not enough data to settle on one explanation, really. That's often the trouble with these crappy videos on Youtube. Far from aiding understanding, they are designed to bamboozle.

Why would this water turn to vapour, though? Boiling water can't boil cold water. I think there is some undisclosed source of pressure in the pipe. It could be water pressure, if this is a pipe connected to a water main. We are not told, and the video snippet carefully cuts off before we can see whether water continues to emerge once the ice plug is out. Or possibly it could be some air pressure built up further along in the pipe, due to freezing and expansion of water within it, causing the air to become compressed. Again we are not told enough. Or it could be something else.