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

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SUMMARY

The energy released when cooling 1 liter of water from 100°C to 25°C is approximately 268,800 joules, calculated using the formula 80°C x 800g x 4.2J. This amount of energy is significant, equivalent to the energy stored in about 27 AA batteries. The discussion confirms that the specific heat of water remains relatively constant across the temperature ranges mentioned, indicating that the energy release per degree Celsius is linear within those ranges. However, it is important to note that this linearity does not hold true for all substances and temperature ranges, particularly during phase changes, which involve latent heat.

PREREQUISITES
  • Understanding of specific heat capacity
  • Basic knowledge of thermodynamics
  • Familiarity with energy units (joules)
  • Ability to perform simple calculations involving temperature and mass
NEXT STEPS
  • Research the concept of specific heat capacity in different materials
  • Learn about latent heat and its implications during phase changes
  • Explore the relationship between temperature change and energy transfer in thermodynamics
  • Investigate practical applications of thermal energy calculations in everyday scenarios
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Students in physics, engineers working with thermal systems, and anyone interested in understanding energy transfer in water and its implications for temperature regulation.

supak111
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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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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.
 
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
 
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.
 
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?
 
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".
 
Will do and thanks.
 

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