Question

Cryogenics has the potential to be useful in a variety of fields, including medicine. Suppose you have engineered a method to successfully deep-freeze and thaw human organs using liquid nitrogen without any freezing damage to the cells and tissue structure. How much heat must be removed from a liver (1.5 kg) to drop its temperature from 310 K to 180 K and freeze the tissue? For liquids and solids, heat capacity at constant pressure, Cp, is approximately equal to heat capacity at constant volume, Cv.

Answer 1

Explanation:

It is known that the specific heat capacity of Liver $(C_{p})$ is 3.59 kJ $kg^{-1}.K^{-1}$

It is given that :

Initial temperature of Liver = Body temperature = $37^{o}C$ = 310 K

Final temperature of Liver = 180 K

Relation between heat energy, mass, and change in temperature is as follows.

                        Q = $m \times C_{p} \times \Delta T$

Now, putting the given values into the above formula as follows.

                    Q = $m \times C_{p} \times \Delta T$

                    Q = $1.5 kg \times 3.59 kJ/kg.K \times (310 - 180) K$

                         =  700.05 kJ

Therefore, we can conclude that amount of heat which must be removed from the liver is 700.05 kJ.