Question

Suppose that instead of using water in the bomb calorimeter, we used acetone. Imagine that the temperature change of the combustion reaction you study in the acetone-containing calorimeter measured 4.83̊C. Calculate the change in internal energy (kJ) for the acetone-containing calorimeter. Comment briefly on the magnitude of this value.

Answer 1

Change in internal energy of system can be calculated by the following equation

dE = Z*dT*(mol.wt/mass) , for acetone, z= 2.15 KJ/kg

Z= specific heat of solvent, dT= change in temperature

If M/m = 1 then dE = 2.15*4.83 = 10.384 KJ

The change in internal energy is 10.384 KJ

If water is the solvent, then dE = 4.184*4.83 = 20.20 KJ

Therefore, the change internal energy for acetone is less compared to water this is due to low specificheat capacity of acetone than water