exchemist

Rather than just offer an answer, let me ask you what ideas do you have about this, first of all?

Added to what?

This is all good stuff. The only unresolved issue now is the bit I read somewhere about absorption of IR by sulphate. I'll have to find that again and re-read.

Plausible. Do you know this is is why sulphate is considered a net anti-greenhouse emission, or is this just reasonable speculation? That sounds like it could be it. So we have three potential mechanisms: - selective IR absorption to block short IR from reaching the ground - efficient reflection/scattering by sulphate - nucleation for formation of high altitude clouds I'll have to try to read something on these to see what I can find.

I can't see how that can explain it because, as far as IR is concerned, CO2 and water would "shade" in the same way. The point about the greenhouse effect, as I understand it, is that incoming radiation of all wavelengths is converted to IR by the Earth's surface, re-radiated from it as IR - and is then absorbed and scattered by CO2 and water, ricocheting around the atmosphere instead of being emitted into space, and thus heating up the atmosphere. Shade as a mechanism can work if fine particles (whether sulphate or other) reflect radiation of all wavelengths (my previous comment about albedo - but in that case why would sulphate be specially effective?) or, I suppose, if they reflect just IR, but if they absorb IR they will heat up the atmosphere, won't they?

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