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How to boil water faster
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tszaboo:
It takes the same amount of energy to boil the same amount of water, that's obvious.
You are asking the wrong question though.
Why are we boiling the water?

Making tea? Desalination? Disinfection? Making soup? Energy storage/generation?
Most of these questions have a lower energy solutions.
themadhippy:
if the pots are the same diameter then the 10 litres,cause 9 litres will be at a higher elevation and reach boiling point at a lower temperature
tunk:

--- Quote from: themadhippy on January 08, 2024, 03:05:41 pm ---if the pots are the same diameter then the 10 litres,cause 9 litres will be at a higher elevation and reach boiling point at a lower temperature

--- End quote ---
Or at a higher temperature because the pressure at the bottom is higher.
coppice:
What do you mean by boil? Reach 100C or bubble? Nucleation issues (e.g. surface contamination in the pots) will affect when bubbling gets going. If you are just looking to reach 100C, then if the heat is applied within the bulk of the water, that is 100% efficient, and the pots with the greatest losses will boil the slowest. Evaporation is usually a big loss, unless the pots have narrow necks, so probably the pots with the greatest total surface area will suffer the greatest loss, and boil the slowest. In a strong draught, maybe losses from the outside of the pots will dominate, and the pots with the greatest total outside surface area will be the slowest.
IanB:

--- Quote from: soldar on January 08, 2024, 11:31:02 am ---The question was asked in another forum but there were a lot of just plain ignorant and stupid answers and the topic died but I think it might be a good thought experiment. The question is

Is it faster to boil 10 L of water all at once (in a 10L pot) or 10 L of water in 1 L pots successively?
--- End quote ---

This is an example of a question that cannot be answered as given, as it will depend on so many unstated assumptions. Each person answering the question may make different assumptions, and so may arrive at as different answer.

The only way to address this question is not to answer it, but to discuss the kinds of assumptions that might need to be made to give an effective answer.

We can give a "spherical cow" answer, by making some very unrealistic assumptions:
1. In both cases we have the same mass of water (10 L = 10 kg)
2. In both cases we are heating the water from the same starting temperature to the same ending temperature (e.g. from 20°C to 100°C).
3. In both cases the rate of heating is identical (e.g. 3 kW)
4. All the heat added goes into the water and none is wasted
5. No heat escapes from the water to the surroundings (perfectly insulated containers)
6. No boiling or evaporation occurs (which will consume additional heat beyond that required for raising the temperature)

By making assumptions such as these, we can observe that the time to bring the 10 kg of water to boiling point will be identical in both cases, since heating water without losses is a path-independent process. To raise a given mass of water from one temperature to another will require the same amount of energy regardless of whether you do it in pieces or as a whole. If the power input is the same in all cases, then the time taken will also be the same.

Now, by varying or relaxing the listed assumptions above, such as by allowing for heat losses, then the answers can change, and this is where the interest may lie.
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