IMAT 2012 Q71 [Specific Heat Capacity]

A block of iron at 100 ^{\circ} C is transferred to a plastic cup containing water at 20 ^{\circ} C.

Which one of the following is NOT necessary in order to find the specific heat capacity of iron?

A. The specific heat capacity of water.
B. The mass of the block of iron.
C. The thermal conductivity of the iron.
D. The final temperature.
E. The mass of water.

The formula that should be used to calculate the SHC of iron here should be:

c= {\frac { ΔE}{m Δt}}, which is derived from E= mcΔt , where
m= mass (kg)
c= SHC {(J/kg^{\circ}C)}
Δt= change in temperature {(^{\circ}C)}
ΔE= change in thermal energy (J)

These values are used once for the iron, but are also used for the water- to be able to understand the amount of energy the iron loses, and the water gains.

This equation will be equated to itself, where equation 1 is in terms of the Iron block, and equation 2 is in terms of the water in the cup.

Either way, we have listed all the values we need- and we can notice that we do not need the thermal conductivity of the iron anywhere here, making the answer C.