A cup of coffee(140g) cools from 75 degrees Celsius down to comfortable room temperature 20 degrees Celsius. How much energy does it release to the surroundings.

Question

asked Jan 9, 2021 98.0k views

1 Answer

Jennet · Answer 1 · 2021-01-16T06:07:48+0000

Energy releases to the surroundings = -32.2 kJ

Heat can be calculated using the formula:

Q = mc∆T

Q = heat, J

m = mass, g

c = specific heat, joules / g ° C

∆T = temperature difference, ° C / K

mass of coffee(m) = 140 g

∆T = temperature difference :

final temperature - initial temperature = 20-75=-55°C

specific heat coffee= specific heat water = 4.18 J/g° C

The heat releases :

$\tt Q=140* 4.18* -55\\\\Q=-32186~J\approx -32.2~kJ$