Energy release from 75c drop in water temp, 1L?

In summary, the conversation discusses the amount of energy released in joules when 1 liter of water at 100C is dropped to 25C, and for every 1C drop in temperature. It also questions if the release of energy is linear and if it takes the same amount of energy to go from 20 to 21C as it does to go from 90 to 91C. The answer is yes, for water, the specific heat is a constant with temperature. However, phase changes also play a role in the amount of energy released.
  • #1
supak111
47
1
Hey everyone can anyone tell me how much energy is released (joules) if you take 1 liter of water at 100C and drop it down to 25C (room temp, reg pressure)? Is it significant amount?

Better even how much energy is released (approximately) for every 1c drop in temp? Is the release in energy linear? Say 90C to 89C vs 50C to 49C, both same amount of energy?
 
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  • #2
supak111 said:
Hey everyone can anyone tell me how much energy is released (joules) if you take 1 litter of water at 100c and drop it down to 25c (room temp, reg pressure)?
Most people here can, but you will benifit more by working it out for yourself.
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/spht.html
... answers all your questions.
Is it significant amount?
Dunno - what do you mean by "significant"?

Niggle:
You mean, 1 litre of water at 100C drop to 25C?
A "1 litter" is "one platform for carrying people on", and "100c" is a dollar.
 
  • #3
Lol. So it basically: 80C x 800g x 4.2J= 268,800J? Or am I not doing this right?

Seeing how a AA battery only has about 10,000J, I would consider that significant ;-). In fact I'm kind of shocked it would take about 27 AA batteries
 
  • #4
That's right - this is why water plays such a big role in temperature regulation. Though it takes 27 AA batteries to heat the water ... it cools down all by itself.

You can check that it makes sense by considering how long it takes for your kettle to bring a cup of water to boil.
 
  • #5
Yea this is true. Is the heating and cooling linear? What I mean is does it take same amount to go from 20 to 21C and it does to go for 90 to 91C for example?
 
  • #6
supak111 said:
Yea this is true. Is the heating and cooling linear? What I mean is does it take same amount to go from 20 to 21C and it does to go for 90 to 91C for example?
In terms of the link I gave you, this question amounts to asking if the specific heat is a constant with temperature... for the temperature ranges you cite, for water, yes. However, this is not generally the case, which is why tables of specific heats also list the temperature where they were measured.

Then there is the case of phase changes - look up "latent heat".
 
  • #7
Will do and thanks.
 

Related to Energy release from 75c drop in water temp, 1L?

1. How does a 75 degree Celsius drop in water temperature release energy?

When water is heated, the molecules within the water gain energy and move faster, causing the temperature to rise. When the water cools down, the molecules slow down and lose energy. This energy is released in the form of heat.

2. What is the source of the energy released from a 75 degree Celsius drop in water temperature?

The source of the energy released is the thermal energy stored within the water molecules. This energy is released when the temperature of the water decreases.

3. How is the energy released from a 75 degree Celsius drop in water temperature measured?

The energy released from a drop in water temperature can be measured using a calorimeter. A calorimeter is a device that measures the heat transfer between two substances, in this case, the water and the environment.

4. Is the energy released from a 75 degree Celsius drop in water temperature significant?

The amount of energy released from a 75 degree Celsius drop in water temperature can vary depending on the volume of water and the surrounding environment. However, in general, this energy release is considered significant and can be harnessed for various purposes.

5. Can the energy released from a 75 degree Celsius drop in water temperature be used as a renewable energy source?

Technically, the energy released from a drop in water temperature is not a renewable energy source as it is simply a transfer of heat energy. However, this energy can be harnessed and converted into usable forms, such as electricity, through methods like geothermal energy. This process is considered renewable as it utilizes the Earth's natural heat and does not deplete finite resources.

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