Using a constant specific heat of 4,184 J/(kg·K), heating 2 kg of water by 10 K requires 83,680 J, or 83.68 kJ. This estimates heat absorbed by the water, not the energy consumed by a real appliance.
Why this works
Use Q = mass × specific heat × temperature change. A difference of 10 °C equals a difference of 10 K. Choose a specific heat appropriate to the material and temperature range; include the container separately if you need its heat requirement.
When this answer changes
Temperature describes a thermal state; heat energy transferred depends on mass and material as well as the temperature change. The simple formula excludes boiling, melting, other phase changes, evaporation, and heat escaping to the surroundings.
Try your own values
Use the sensible heat calculator to test your inputs. Save two scenarios to compare results, or copy an input link to revisit your calculation.
