Chapter 28, Problem 1RQ

List the evaporating temperatures for liquid nitrogen and CO₂: _____and____.

To determine

The evaporating temperature of liquid nitrogen and ${\text{CO}}_2$.

Answer to Problem 1RQ

The evaporating temperature of liquid nitrogen and ${\text{CO}}_2$ is $-195\text{°C}$ and $-78.5°\text{C}$ respectively.

Explanation of Solution

Evaporation is a process in which a liquid turns into gas. The temperature at which evaporation starts is called evaporating temperature. Evaporation can occur at any temperature and pressure greater than zero Kelvin or absolute zero temperature. The temperature at which evaporation starts is called the evaporating temperature of that liquid. Evaporation is different phenomenon than boiling. Boiling starts at a particular temperature while the evaporation can takes place at any temperature greater than the absolute zero temperature.

Liquid nitrogen is colorless which starts evaporating at $-195\text{°C}$. It is a diatomic liquid. It has covalent bonding between its $\text{N}$ atoms and exists as ${\text{N}}_{\text{2}}$.

Carbon dioxide consists of a carbon atom and two oxygen atoms. Carbon atom is covalently bonded with both of the oxygen atoms. They are linked with two double bonds and can be written as $\text{O}=\text{C}=\text{O}$. Carbon dioxide changes its phase from solid to gaseous without converting into liquid phase. The temperature at which the transformation takes place is $-78.5°\text{C}$.

Conclusion:

The evaporating point for liquid nitrogen is $-195\text{°C}$and for ${\text{CO}}_2$ is $-78.5°\text{C}$.