Consider two identical iron nails: One nail is heated to 95 °C, the other is cooled to 15 °C. The two nails are placed in a coffee cup calorimeter and the system is allowed to come to thermal equilibrium. What is the final temperature of the two nails?

Answer 1

Is water in the calorimeter"? If not, then
mass Fe x sp.h.Fe x (Tf-95) + mass Fe x sp.h.Fe x (Tf-15) = 0
Tf = 55 if I did it right. Check my work. Since mass and sp.h. are the same, the easy way is to assign arbitrary numbers to mass and sp.h. (I used 1 to make it easier).