How much heat is required to raise the temperature of 250ml of water from 20.0 d

Question

How much heat is required to raise the temperature of 250ml of water from 20.0 degree C to 35.0 degree C? How much heat is lost by the water as it cools back down to 20.0 degree C? How much heat does 25 g of aluminum give off as it cools from 100 degree C to 20 degree C? The specific heat capacity of aluminum is 880 3/kg degree C. An amount of heat is added to a mass of aluminum and its temperature is raised 57 degree C. Suppose the same amount of heat is added to the same mass of copper. How much does the temperature of the copper rise? The specific heat capacity of aluminum is 0.21 cal/g degree C. The specific heat capacity of copper is 0.093 cal/g degree C.

Explanation / Answer

Expression for heat energy:

Q = m*c* delta T

here c is the specific heat capacity of material, in this case, water.

c(water) = 4.18J/ g* K and mass, m = 250 ml = 250 g = 0.250 kg and

change in temperauture = 35 - 20 = 15 K

Substitute numerical vlaues

Q = ( 0.250 kg ) ( 4.18 J/g*K ) ( 15 K ) = 15.675 J

In three significant digits

Q = + 15.7 J

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In order to cool the water for same temperaure range, the required heat is same, but the process

is reverse in direction. Because, the heat is proportional to change in temperature,

Q = - 15.7 J

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