Question

An unknown substance has a mass of 0.125 kg and an initial temperature of 79.8°C. The substance is then dropped into a calorimeter made of aluminum containing 0.285 kg of water initially at 21.0°C. The mass of the aluminum container is 0.150 kg, and the temperature of the calorimeter increases to a final equilibrium temperature of 32.0°C. Assuming no thermal energy is transferred to the environment, calculate the specific heat of the unknown substance.

Answer 1

Solution :-

Given data,

The mass of the unknown m = 0.125kg

the mass of the calorimeter mw = 0.285kg

the mass of the container mAl = 0.15kg

from calorimetry

           mcΔT = [ mw c + mAl cAl ] ΔT'

Therefore the specific heat of alunimum is

           c = [ mw c + mAl cAl ] ΔT' / mΔT

               = [ 0.285 (4186) + (0.15)(900)] (32 -21) / (0.125)(79.8 - 32)

               = 2444.872 J/kg. ⁰C