Question

A student heats 100 g of aluminum to 60°C. He places it in 100g of water at 20°C. Over time, what will most likely happen?

Answer 1

They will come to the same temperature (thermal equilibrium) somewhere between 20°C and 60°C.
Assuming no heat loss to the surroundings:

mAl cAl (TAl,i − Tf) = mw cw (Tf − Tw,i)

With mAl = mw = 100 g, cAl ≈ 0.90 J/g·°C, cw ≈ 4.18 J/g·°C:

0.90(60 − Tf) = 4.18(Tf − 20)

Solve → Tf ≈ 27.1°C.

So the aluminum cools and the water warms until both are about 27°C.