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# Heat content or Btu value of water at various temperatures?

Help??

Where can I find the Btu value or heat content of water at various temperatures such as 50, 60, 70, 80, 90 & 100 degrees F? Say 1 lb of water.

Is it also generally safe to say that if the water is in contact with another surface, that the water will give up its heat content so long as the adjoining mass is cooler than the water??

For instance, if a 1 lb block of wood at 65 degrees F is submerged in water that is 80 degrees F, how much heat will flow from the water to the wood?

How does the thermal conductivity of the wood play into this?? Or does thermal conductivity relate only to the passage of gases through a substrate?

#### Solution Preview

(a)
I believe what you actually need is not the total energy in a pound of water but the change of this energy with the change of temperature.

This is addressed by heat capacity which in turn is determined by specific heat.
The specific heat of water varies very little between the temperatures you mention, so you can take it to be the same and its value is

c = 1 Btu / (Lb*ºF)

(see e.g. http://www.refrigerationbasics.com/1024x768/definitions1.htm).

The fact that it is exactly 1 is not a coincidence, because the heat capacity of 1 pound of water per ºF serves as a DEFINITION of Btu.

Given some mass m of water, to change its temperature by some &#916;T, we need the amount of energy

&#916;Q = c*m* &#916;T.

For instance, to raise the temperature of 1 pound of water from 50ºF to 60ºF, we would ...

#### Solution Summary

Where can I find the Btu value or heat content of water at various temperatures such as 50, 60, 70, 80, 90 & 100 degrees F? Say 1 lb of water.

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