Calculate change in entropy when 1kJ of thermal energy flows from a hot reservoir at 500°C.

Answer 1

We can solve for the change in entropy for the water using the equation ΔS = Q/T, where ΔS is change in entropy, Q is the heat transferred (in J), and T is the temperature (in K).

If 1kJ of thermal energy is leaving the reservoir, the reservoir has a Q = -1kJ.

Think about why this is a negative number -- is the energy leaving or entering the system?

Q = -1kJ = -1000J

Convert the temperature from °C to K by adding 273.15:

T = 500°C = 773K

Now plug Q and T into the equation ΔS = Q/T

ΔS = Q/T

ΔS = -1000J / 773K = -1.29 J/K