Question

The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the final temperature when 1.00 kcal of heat transfers into 1.00 kg of the following, originally at 20.0ºC : (a) water; (b) concrete; (c) steel; and (d) mercury.

Answer 1

Answer: final temperatures will be

a) water 21 C

b) concrete  20.005 C

c) steel   20.008 C

d) mercury  53 C

Explanation:

Change in temp dT = dH / (mass x specific heat)

Specific heat of these materials can be found from many sources:

water = 1 kcal / kg C

concrete = 210 kcal / kg C

steel = 114 kcal / kg C

mercury = 0.03 kcal /kg C

So dT (water) from 1 kcal heat into 1 kg water = 1 kcal / (1 kg x 1 kcal/kg C) = 1 C therefore the final temperature is 20 + 1 = 21 C

But dT (steel) = 1 kcal / (1kg x 114 kcal/kg C) = 0.008 C so the final temperature is 20 + 0.008 = 20.008 C

The results for concrete and mercury are calculated in the same way