Heating Water Chemically

You have not provided enough information for anyone to help you.

1. The first and most important question is: what temperature does the water start at?

2. Secondly, how fast must it reach the final temperature?

There are many ways to heat water chemically, depending on what you need it for.

3. For example, does the water need to remain clean, for drinking or bathing? If not, chemicals that combine to produce heat or that react with water to produce heat may be added. These often leave poisonous or hazardous by-products.

4. Can the water be pumped out, heated, and pumped back? This could be done with either constant or varying water levels in the tank.

5. Does the tank need to remain free of solids? If not certain metals that react with water do produce heat and light, but may also leave a residue. Care must also be taken that they do not settle on the bottom or at one side and melt a hole in the tank.

There are probably more questions, but these are the first ones that popped into my head.

You need to be more specific.

Thanks for the reply

1) Water starts at abort 10 degree Celsius

2) As fast as possible without destroying or damaging the acryl tank

3) The water should not be poisoned. A person has to swim in it later

4) Water can not be pumped out/in again because it would require time.

5) Solids would not be a problem a slightly discolor would be fine. To much visibility lost would not be acceptable.

regards Rob Oudendijk

That IS a tall order!

Well, by definition, a calorie is the amount of heat required to raise one gram (volume of one ml.) of water by one degree Celsius. Your ΔT would be 25°C - 10°C = 15°C. So your heat required would be:

Q = 4000 liters x 1000 ml./liter x 15°C = 60 million calories = 60,000 Kilocalories

The conversion to BTU is a factor of 3.966, and to kilojoules the factor is 4.184, so your energy requirement is rougly 238,000 BTU or 251,000 kilojoules.

I did see one reference that said that dissolving sodium hydroxide (NaOH) in water is so exothermic (heat liberating) that care must be taken not to melt the plastic container. I would think that the proper amount, well distributed and mixed would work for you.

Now, NaOH is what is known as a strong alkali or base, and this would be hazardous to a human body. Strong acid/base reactions also liberate heat, called the Heat of Neutralization. A common experiment to show this is to react NaOH with HCl (hydrochloric acid). Besides heat, the resultant products are nothing more than H₂O and NaCl, water and salt. I once saw my High School chemistry teacher do this, and he drank the result (with no ill effects)! Care must be taken however, because HCl and NaOH are both very caustic to human flesh. You can tell if the reaction is complete, with no left over chemicals, if the pH is neutral. This can be done with a pH meter (similar to those used in swimming pools) or by use of a non-toxic chemical pH dye indicator, which changes colors, usually from blue or red to clear.

So here is one possible scenario. Rig the water tank to release dry NaOH powder spread evenly through out for quick dissolving. Some type of mixing device would help. That should raise the temperature part way. The water tank may already contain the pH indicating dye or you could have a sensor put in.

Then quickly add and mix in the proper amount of HCl to neutralize the NaOH and provide additional heat. If the pH is neutral (not acidic or basic) it would be safe for someone to bath in this pure salt water.

There may be other possibilities. I would consult with a Chemist (and I do not mean, in the English sense, a pharmacist!) for the proper amounts. You might also expermiment on a small scale to get the temperature change in the time you are looking for, then scale up the amounts as necessary. For example, try a 4 liter tank until you get what you want. Then multiply the amounts by 10X for a 40 liter tank, and see if the results are repeatable. You may even want to try 400 liters before scaling up to 4000 liters. Be very careful to avoid splashing caustic chemicals and to mix all reactions thoroughly.

Whooo thanks for all the information. I will research more.

regards
Rob Oudendijk

Hi this is Gyan, frm Thailand.

i had posted similar requirement a few days back,

i have tried with dissolving caustic and then reacting it with HCL, water does really heats up by 10-12 odd deg C, but the chemical handling and processing is a big issue.

the resultant water is salty and can not be used for further purpose, u might generate with disposal of the 1400 gallons of water evrytime u want to take a bath, environment concern.

Although my requirement is not a delta of 10 Deg, i need a delta of 3-4 deg C with no ill effects to human or to environment.

is there something which can just simulate hotness to the skin, ( Eg, Menthol in water can give u temporary very cold feeling )?

there must be some chemical component doing the magic......?

Please post if u come across something like this.......