A 1 mol piece of copper at 400 K is brought in contact with another 1 mol piece of copper at 300 K, and allowed to reach thermal equilibrium. The entropy change for this process is________   (in J K^-1 to three decimal places).

Given: Specific heat capacity of copper (between 250 K and 500 K) is 22.6 J K^-1mol^-1. Assume that the system containing the two pieces of copper remains isolated during this process.