Thermodynamics
The relationship you need is q = mcΔT where q is heat (in cal or Joules), m is mass (in g), c is specific heat, and ΔT is the change in temperature (in degrees C or K)
You are given: c = 1.75 cal/(g•°C)
m = 2.56 kg; convert to g, 2.56 kg • 1000 g / 1 kg = 2560 g
Tinitial = 23°C
Tfinal = 191°C
ΔT = Tfinal – Tinitial = 191°C – 23°C = 168°C
q = mcΔT
q = (2560g)(1.75 cal/(g•°C))(168°C)
q = 752 640 cal