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Is this really a homework question or just a request for understanding of material you have been presented with in a course or read ? I ask because it looks much more like the latter and such questions can legitimately be asked in the main Chemistry sections. OK so there are several different classification schemes for chemical reactions. Each has its own point of view and the schemes are not mutually exclusive. So you first list is about reactants and products. That is what substances you start with and what substances you end up with. Say A + B = C - combination A = B + C - decomposition or dissociation AB + CD = AD + CB - replacement or elimination and so on. There are further reactions types than your first list in this viewpoint. Your second list narrows down these wider categories in some way. So Acid + Base = Salt + Water Is an elimination reaction where CB is always water and AD is always the salt. (This has been extended beyond water in more advanced Chemistry) If the reaction is in solution and AD is precipitated then this is also a precipitation reaction. So you can see some overlap in the categories beginning to appear. Oxidation is the addition of oxygen or the removal of hydrogen Reduction is the removal of oxygen or the addition of hydrogen Since combustion is one of these (which one ?) It is a redox reaction. Note that all these classification types start with substances and end with different substances. In more advanced Chemistry your will meet others views which are about what goes on during the reaction and the movement of electrons and/or protons from one substance to another. These may be called reaction mechnaism views. Where are you in your studies to have been given the first list as the basic 5 ?

What is meant by virtual (virtually is an adverb which refers to verbs, not nouns) is my point. Yes we do understand virtual and have been using it for centuries. Does you eye see the virual image obtained through a magnifying glass ? What is the difference between a real and virtual image ? If you understand the difference between pressure and force you are using a good example of another virtual phenomenon. Consider a gas. Imagine a frame somewhere in that gas defining an area. What is the pressure across that frame and is a force acting ? The frame and its area are virtual as pressure is only exerted on the boundaries of the gas. In other words it is only realised by the interaction with the real world around it, just like the quantum virtual particle.

But this is strictly speaking off topic. I admit to discussing tea rather than soup but the principle is the same. So the topic is what is the difference between blowing on your hands and blowing on your soup (or tea). ? So you can't dismiss the subject of the topic.

Thank you for your thoughts. But I can only suggest you read very again carefully both the opening post and what I actually wrote. What you have just written is incompatible with both (and with the scientific method as well).

Has everybody (MarkE in particular) given up on this one ?

Well I'm sorry I can't see any hostility in my response. I even suggested you do exactly that - hear and evaluate the evidence, but from the medical professionals directly concerned. Ultimately the decision is yours alone.

I'm not suprised if you tried to study it via Carnot cycles. That really is the hard way. Thermodynamics divides things into a system and the rest of the universe (ie the surroundings). To do this successfully it must always specify the system boundary. Having done this state variables (preferably directly measurable ones) are introduced for both the system and its surroundings. Pressure, volume and temperature being the most recognisable. Now it was found that the area under a P - V plot was equal to the mechanical work that is exchanged across the system boundary between the system and its surroundings. This leaves temperature and a similar variable was sought to pair with temperature to calculate the heat energy exchanged across the boundary. Entropy was the name given to this variable. So the area under a T - S plot is the heat energy that passes across the system boundary. Unfortunately entropy, unlike P, V and T is not directly observable so we use measured tables instead. That's all there is to it.

John is that rare breed of Scotsman who possesses a grand sense of humour. And of course, burn is the Scottish for a stream. The additional double entendre was unintentional and unnoticed by me, until you pointed it out. Since no large deflection is required I was thinking in terms of a diaphragm deflecting and maybe pushing a rod. The way to calculate this is not from the equations because water is an exception to the normal pattern. You need to get out a set of 'International Steam Tables' - a quick look shows mine are in the garage - and read off the entropy change on a T - S diagram to obtain the energy flows easily. I don't have a convenient glacier to effect the freezing part of the cycle or a convenient hot spring/geyser to provide the thawing, and even if I did they would still be part of the system and their entropy changes need to be included.

Oh dear was my spelling really that sloppy ? 😳 Sorry all.

Don't you need a 'wee burn' to run a stream engine ? 🙄

Yes perfomance of the cycle a requirement of the second law. So another way to put it is that the work obtained from the expansion of the ice will be less than the heat required to complete the cycle and thaw the ice, ready for the beginning of the next cycle. Such situations were exactly why Maxwell, Clausius and others stated the second law in cyclic format, as I have already noted.

Th The acceleration needs to be negative so that the calculation gives the correct direction to the calculated forc in the final eauation F = ma. ie the force is a retarding force.

Thermodynamics is an experimental science. The OP was doing pretty well until he got to this Not really, as a bit of simple experimentation shows. 1) Breath out through a wide open mouth and compare the thermal effect on your hands and the cup of tea. Pretty ineffective cooling on the tea and heating on the spread open hands. Slight heating on cupped hands. 2) Breath out through pursed lips Effective cooling on both the tea and the spread open hands Effective heating on cupped hands So pursing the lips is not the controlling factor to make the difference. So what is ? Well cupping the hands seems to lead to substantially increased hand heating in all cases so lets deal with this first. Cupping the hands forms a small, if leaky, chamber into which the exhaled air is drive, increasing its pressure. Work is done on the air increasing its internal energy. This work is done by the chest muscles of the body as can be felt during the exhalation. Thie work quickly degrades to heat which transfers to the chamber walls (hands) as the atmospheric pressure is reasserted. So that is what warms the hands . If you blow on the spread hands or the tea, evaporation is enhanced as already noted, which process carries heat away from the natural moisture on the hands or the surface of the tea. This occurs whether the lips are pursed or not. The difference is the cupping of the hands.

You have not analysed your heat engine correctly since you have missing elements. The apparatus to cause this should be included So yes If you allowed the ice to expand in a non destructive way by compressing something, this compression could be partly extracted by causing it to do useful work. But you analysis should include the work input to the freezing apparatus which will be greater than the work recoverable by the compression. Remember also that the classical second law applies to a cyclic process, and may be 'violated' in part of a cycle. A bomb is not a cyclic process.

Ok so I know you said deceleration, but in your calculations you should use a negative acceleration. So again how did you arrive at +2m/s2 ? Did you use the formula v = u + at ?

So how do you explain standing waves ?

I'd say it starts with writing down and understanding the reaction equations, noting that H2sO4 is a diacid. Have you done this at least ?

Yup +1 I say this because all the figures for adverse reactions are out of date by a long way. The number of such reactions has been reducing (quite dramatically although the numbers are very small anyway) because as the vaccine programme has progressed so has the method of vaccination. The UK is well ahead of the curve (apart from Israel which is a special case) because it started early and got on with the job. At the beginning there was little screening and sevaral reaction cases occurred. Subsequently the vaccinators started asking more questions designed to weed out those most likely to present a reaction. There was a marked difference between the screening discussion immediately prior to my first Pfizer shot and my second one 12 weeks later. So yes go for the shots, but make sure you discuss known allergies and other conditions (I take it you are not pregnant) with the medics. Then your chances of something really bad happening will be virtually zero. They just did a survey in the UK and most people (like me) found no reaction to the jab. The commonest reaction was a slightly sore arm for up to a few days.

How can I until you explain exactly what you mean by 'virtual' in Philosophy ? There are many effects in Science that are conveniently handled by prefixing the word virtual, although its meaning may vary from application to application. and that is without properly discussing the meaning of particle and exist. Does the place described by 'What Three Words' exit for the three words virtual, particles and exist ?

I am not sure I would regard any of these as scientists. Engineers yes. This is not meant to detract in any way from their achievements however. Perhaps some better examples of true scientists might be Alfred Nobel or the Wright Brothers. Then again perhaps we should distinguish between career scientists ie those who earned their living from it eg Faraday and those who were already rich enough not to need to make money from their work eg Cavendish or Newton. Career scientists are more the norm these days, but I don't think their remuneration is that spectacular compared to say doctors of medicine. Some have made substantial sums from their work by careful commercial application via a company and a few in publications (books). Sadly quite a few have died penniless or near penniless. The range of circumstaces and outcomes is enormous.

A picture of your apparatus perhaps ? Here is a Royal Society of Chemistry diagram of such a cell, including the requested reactions. Is your air cathode porous carbon of some sort ? The reaction requires oxygen from the air to permeate through it.

Yes Yes How ? I think you need to know the time it takes for this to happen or the distance over which it travels during this time.

That's not as I understood your original description. Both others and myself took these to imply a row of photons which do not move and are therefore stationary. Please discuss this claim.

I don't know if you realise just how small these anvil instruments are, or quite how the 'pressure' is developed. Why do you think this would increase at the bottom of the ocean ? And how much fuel do you think you could generate this way ? I'm sure there are lots of reasons Man wants to put bases into difficult conditions - Antarctica, Lunar, Space etc - so why not the bottom of the ocean ? Having asked all that, full marks for dreaming. +1 Two books you might find interesting. Call Me Joe is a science-fiction novella by Poul Anderson of a 'manned' base on Jupiter. Poul was and hugely imaginative scfi author basing most of his stuff on small extensions to known science. Journey to the Centre of the Earth by David Whitehouse (not the Jules Verne novel) is real science and shows how diamond anvils have revolutionised the study of the structure of the Earth and deep earth materials.

Gosh my head hurts. What do you have against poor old gravity. First you say there is no gravity But you retain terms which only have meaning in the presence of gravity To whit 'up' and 'down' and 'vertical' and 'horizontal'. Then you say you can apparantly switch gravity on and off at will.