Question

A 1.00 kg gold bar at 1010 K is dropped into 0.750 kg of sand at 25 °C. Assuming no heat is lost to the atmosphere, what is the final temperature of the sand?

Answer 1

What's the specific heat of the sand?

[mass Au x specific heat Au x (Tfinal-Tinitial)] + [mass sand x specific heat sand x (Tfinal-Tinitial)] = 0
Solve for Tfinal. Of course you know Tf for the sand is the same as Tf for the Au bar.