How much energy, in joules, is released when 17 kilograms of granite is cooled from 45°c to 21°c?

a. 327,992.8 j
b. 365,575.3 j
c. 901,980.3 j
d. 785,662.8 j

Energy or heat can be calculated in terms of the mass, temperature, and specific heat of a substance. This is given by the equation:

U = mCpΔT = mCp(Tf-Ti)

where:
m = mass
Cp = specific heat
ΔT = temperature difference

For this problem, you need to get the specific heat of granite which can be found in reliable chemistry/engineering books or websites. According to Engineering Toolbox website, the Cp of granite is 790 J/(kg-°C).

U = 17 kg (790 J/(kg-°C)) (21-45) = - 322,320 Joules

*Note: the sign is negative because energy was released

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