Question

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

A. 785,662.8 J
B. 901,980.3 J
C. 365,575.3 J
D. 327,992.8 J

Answer 1

the awnser would be D

Answer 2

The final answer is -322, 320 Joules. The solution for the problem is:

The equation that must be used in this problem is:

U = mCp(Tf-Ti)

where:
U = energy released or absorbed in Joules
m = mass in kg
Cp = specific heat of material in J/kg-C
Tf = final temperature, C
Ti = initial temperature, C

Looking up the Cp of granite gives a value of 790 J/kg-C.

U = 17kg (790 J/kg-C) (21-45)
U = - 322, 320 Joules (negative means heat is released)