Question

How much heat is evolved when 22.5 grams of a food sample changes the temperature of 0.54 kg of water by 5.2 degree C. Assume specific heat to be 4.18 J/g/C

Answer 1

By energy of conservation

Heat evolved by food sample = Heat absorbed by water

Now,

Mass of water = 0.54 Kg = (0.54×1000) g = 540 g

Heat absorbed by water

= Mass × specific heat × temperature change

= 540 (g) × 4.18 (J/goc) × 5.2 (oc)

= 11737 J

= (11737/1000) KJ

= 11.74 KJ ( 4 significant figures) .

So, total amount of heat is evolved = 11.74 KJ .

[ Now,

Heat evolved per gram of food sample is

= (11.74/22.5) = 0.522 KJ/g = 522 J/g ]