posted by Fred on .
A portion of an electric circuit connected to a 7 ohm resistor is embedded in 1.20 kg of a solid substance in a calorimeter. The external portion of the circuit is connected to a 100 volt power supply.
(a) Assuming that all the heat generated by the resistor is absorbed by the solid substance, and that it takes 4 minutes to raise the temperature from -10 to 50 degrees C, calculate the specific heat for the substance.
(b) At 50 degrees C, the substance begins to melt. The heat of fusion is 4.5 x 10^5 joules per kilogram. How long after the temperature reaches 50 degrees C will it take for all of the substance to melt?
(a) Calculate the rate of heat transfer to the substance using
P = V^2/R. Multiply by 240 seonds for the number of Joules.
That energy divided by the mass and 60 C is the specific heat
(b) time required =
(Mass)(Heat of fusion)/(Power)
We will be happy to check your work