exchemist

Interestingly, a lot of articles on the effects of eruptions on climate mention sulphate aerosols in the stratosphere exerting a cooling effect. One or two tantalisingly refer to IR absorption by these particles. But I have trouble understanding this, as absorption of IR by CO2 (and water) is exactly what gives rise to the greenhouse effect. So how can what seems to be the same thing cause cooling? If it were a process of reflection, i.e. increasing the albedo of the upper atmosphere to reduce the sunlight incident on the surface of the Earth, that would be something I could understand. But in that case, why would sulphate aerosols be particularly effective? Surely any old dust grains might do the job? Does anyone know?

Ha ha.

You're a bit of a one trick pony, aren't you?

Sorry, I really can't be bothered to wade through all this, er, stuff. Format it properly or I'm out.

Yes, well, kinetic energy has to be specified with respect to a frame of reference, because velocity is relative. Why can't you post in normal length lines? This style is very exhausting to read. It makes one question whether it is worth the trouble.

Do you know what specific heat capacity is? https://chempedia.info/info/calcium_carbonate_specific_heat/

What?

Nowhere. They could have said “underwent oxidation readily”, which in my view would have been better English. It’s just a qualitative statement about what they observed.

But you asked about calcium carbonate. And neither has anything to do with hurting humans.

My audiologist is called Pebbles - rather oddly for such a striking, statuesque black girl. While I'm sure it seemed like a good idea when she was a baby, I feel it hardly does her justice now. She could row at 6 in an VIII. But I am digressing.........😃

What if the sky was made of concrete? Forget it. We can't hope to control volcanic eruptions.

Definitely a case of “Don’t try this at home”. Nickel carbonyl is appallingly dangerous to health and carbon monoxide, which you would need, is also pretty lethal.

Show us how you are going about this, first.

What are you talking about?

Per mole of what? If you mean per mole of water, taking water to be the principal component of the human body, then 4.2J raises the temperature of 1g by 1C deg. The MW of water is 18g, so 4.2 x 18 =75.6J raises the temperature of a mole of water by 1C deg. So 63.6kJ would be enough to raise its temperature by 63.6x 10³/75.6 = 841C, if there were no change of phase. I'll leave the rest to you.

Hmm, I see what you mean.

Look up Newton’s shell theorem. That explains why the mass at a radius greater than the location of the red dot has no gravitational effect on it.

Aha, I see. But this is at very high temperatures. In fact, a moment's thought should tell you the reaction won't go at room temperature, because in this system the urea is a supplied as a solution in water. So obviously that is fairly stable. Regarding the kinetics, I imagine you won't need a catalyst if the solution is sprayed into the combustion chamber, or into hot exhaust, at >500C. (Enzyme catalysts would obviously be no use in such a situation anyway.) Also, this is a reaction in which 2 molecules react to generate 3 molecules. The entropy change for such processes tends to be favourable, so the reaction will be thermodynamically more favourable at higher temperatures. (ΔG = ΔH -TΔS)

No, because all the combinations are soluble. Generally you get that type of reaction when one of the possible salts is a lot less soluble than the others, i.e. it has a lattice that is so stable that the ions to prefer to form crystals than stay dissolved. In such a case, that salt will precipitate out, leaving behind the ions it does not need.

Can you link to where in "the wiki" you saw this? All the links I saw say you need an enzyme (urease) to catalyse this decomposition. Here is a procedure for doing that: https://edu.rsc.org/download?ac=12704

All four ions will remain in solution independently. If you evaporate the water, you may get a mixture of NaCl, CaCl2, NaOAc and Ca(OAc)2, since all are stable salts. However, to find out how much of each you get, you would need to determine the free energy of crystallisation (or solution) for them all, as some combinations will produce lower energy states than others, depending on the lattice energy and the entropy change. You may even get mixed salts like CaClOAc, if there is a suitably low energy crystal structure for that combination.

OK I didn't explain this very clearly in my previous post. A shell is a set of orbitals sharing the same principal quantum number, n. All the elements in a given row of the Periodic Table have their outermost electrons in the same shell, i.e. with the same principal quantum number. For example, elements of the second row, starting with Li, have outermost electrons in the n=2 shell. Next there are subshells. A sub-shell is is a set of orbitals having the same principal, n, and azimuthal (or angular momentum) quantum number, l. So in the second row, electrons can go into the 2s or 2p subshells. The s subshells have l=0, p subshells have l=1, d subshells have l=2 and f subshells have l=3. Finally we have orbitals themselves. These are distinguished by the orientation of the angular momentum, which is set by the 3rd quantum number m(l). Each orbital comprises a pair of quantum states which have identical orientation in space, but with opposite spin orientation of the electron. So for example every p subshell has 3 p orbitals, perpendicular to each other, which you can treat as orientated along x, y and z axes. Each one can have 2 electrons in it, one with spin "up" and one with spin "down". In chemistry we tend to treat orbitals as if they are quantum states, each of which can have zero, one or two electrons in it. Strictly speaking they are not, because you need to specify the spin quantum number too in order to define an individual quantum state properly. But since spin orientation can only have 2 values "up" or "down", and since the spatial orientation of the orbital is what is relevant for chemical bonding, it is convenient to think of the orbital as the basic building block of electronic structure in the atom, each of which can accept a pair of electrons.

No, because the question was not adequately specified, as the progress of the subsequent discussion shows.

Sodium bicarbonate is a very weak alkali - a saturated solution of it only has a pH of 8-9 or so. But I imagine some of the dyes may eventually oxidise over time and cease to function, so it may be better to replace it. Universal indicator contains several dyes that change colour at different pH values. There is a Wiki article that is quite helpful:https://en.wikipedia.org/wiki/Universal_indicator

OK, but isn't this the "observer effect", rather than a true demonstration of the HUP?