Section 16.2
� Calorimeter- an insulated device used for measuring the amount of heat absorbed or
released during a chemical or physical process.
� To use a calorimeter, a known mass of water is placed in an insulated chamber of the
calorimeter in order to absorb energy that is being released
Determining Specific Heat
� You can use a calorimeter to determine the specific heat of an unknown metal
� Suppose you put 125 g of water into a foam cup calorimeter and find that its initial
temperature is 25.6 degrees C.
� Then, you heat a 50 g sample of an unknown metal to 115 degrees C and put it in the
water
� The heat from the metal flows into the water and the temperature of the water rises
� The flow of heat stops when the metal and the water are the same temp.
� After this has happened, they both have a temperature of 29.3 degrees C
� Use the equation learned in section 16.1 to find the amount of heat gained by the
water and lost by the metal (should be the same)
q = c x m x change in T
� First calculate the heat gained by water sing the specific heat of water
(4.184 J/g degrees C)
qwater = 4.184 J/g degrees C x 125 g x (29.3 degrees C � 25.6 degrees C)
qwater = 1900 J
� The heat gained by the water equals that heat lost by the metal
qmetal = 1900 J = cmetal x m x change in T
1900 J = cmetal x m x change in T
� Solve for the metal, cmetal, by dividing both sides by m x change in T
cmetal = 1900 J
m x change in T
� The change in temperature for the metal is the difference between the final
temperature and the initial temperature (115.0 � 29.3 = 85.7 degrees C)
� Substitute the known values for m (50.0 g) and change in T (85.7) and solve
Cmetal = 1900 J = 0.44 J/g degrees C
(50.0 g)(85.7 degrees C)
� The unknown metal has a specific heat of 0.44J/ g degrees C
