Change in thermal energy= 230* (difference in temperature)
= 230* (90-12)
= 17940 calories (or cal)
M=MASS OF WATER
T=CHANGE OF TEMPERATURE
SO YOUR ANSWER IS
Thermal energy is measured in units of calorie, where 1 calorie is defined as the amount of thermal energy required to raise the temperature of 1 gram of water by 1 degree C. Also the total thermal energy required to raise the temperature of a given mass of water (m), from initial temperature (t1) to a higher temperature (t2) is given by the formula:
Thermal energy in calories = m*((t2 - t1)
It is given:
m = 230 g
t1 = 12 degrees C
t2 = 90 degrees C
Substituting these given values in equation for thermal energy we get:
Thermal energy = 230*(90 - 12) = 230*78 = 17940 calories
The change in thermal energy of water is same as the thermal energy used for raising its temperature.
Change in thermal energy = 17940 calories.