Liquid nitrogen, which has a boiling point of −195.79°C, is used as a coolant and as a preservative for biological tissues. Is the entropy of nitrogen higher or lower at −200°C than at −190°C? Explain your answer. Liquid nitrogen freezes to a white solid at −210.00°C, with an enthalpy of fusion of 0.71 kJ/mol. What is its entropy of fusion? Is freezing biological tissue in liquid nitrogen an example of a reversible process or an irreversible process?

Explanation:

Entropy is measure of disorder so as we lower the temperature of gas , its entropy decreases .

Hence at - 200°C entropy of nitrogen will be less than that at - 190°C .

At freezing point ,

entropy of fusion  = latent heat / freezing temperature

= .71 kJ / ( 273 - 210 )

= 710 / 63 J mol⁻¹ K⁻¹ .

= 11.27 J mol⁻¹ K⁻¹ .

entropy of fusion = 11.27 J mol⁻¹ K⁻¹ .

It made it possible to actually see cells.

Explanation: With the development and improvement of the light microscope, the theory created by Sir Robert Hooke that organisms would be made of cells was confirmed as scientist were able to actually see cells in tissues placed under the microscope.